Hi, I dont write code, just do the more basic customization of SF, however, I have a customer who needs a calendar exchange code. To explain, if they enter a standard date field, they need a link to display the jewish Calendar date for that day, month, year. (it changes every year and repeats itself every 19 years)
i actually have a jave code sample that does this, i'm not sure how to integrate it into a SF instance. The code is as follows:
can anyone help me out as to what merge fields/functions to input to tell it to display that particular date in the hebrew date.  Feel free to use the code as stated below, the site to donate or contact the developer is below as well.
thank you!!
Hudi Falik



/* kdate.js - Kaluach Javascript Hebrew date routines
 *   Version 0.03 (beta release)
 * Copyright (C) 5760 (2000 CE), by Abu Mami and Yisrael Hersch.
 *   All Rights Reserved.
 *   All copyright notices in this script must be left intact.
 * Based on the formula by Gauss
 * Terms of use:
 *   - Permission will be granted to use this script on personal
 *     web pages. All that's required is that you please ask.
 *     (Of course if you want to send a few dollars, that's OK too :-)
 *   - Use on commercial web sites requires a $50 payment.
 * website: http://www.kaluach.net
 * email: abu-mami@kaluach.net
 */

function makeArray() {
    this[0] = makeArray.arguments.length;
    for (i = 0; i < makeArray.arguments.length; i = i + 1)
        this[i+1] = makeArray.arguments[i];
}

var hebMonth = new makeArray(
    'Nisan', 'Iyyar', 'Sivan', 'Tammuz', 'Av', 'Elul',
    'Tishrei', 'Cheshvan', 'Kislev', 'Tevet', 'Shevat',
    'Adar', 'Adar I', 'Adar II');

var civMonth = new makeArray(
    'January', 'February', 'March', 'April', 'May', 'June',
    'July', 'August', 'September', 'October', 'November', 'December');

var weekDay = new makeArray(
    'Sun', 'Mon', 'Tues', 'Wed', 'Thur', 'Fri', 'Shabbat');

function Gauss(year) {
    var a,b,c;
    var m;
    var    Mar;    // "day in March" on which Pesach falls (return value)

    a = Math.floor((12 * year + 17) % 19);
    b = Math.floor(year % 4);
    m = 32.044093161144 + 1.5542417966212 * a +  b / 4.0 - 0.0031777940220923 * year;
    if (m < 0)
        m -= 1;
    Mar = Math.floor(m);
    if (m < 0)
        m++;
    m -= Mar;

    c = Math.floor((Mar + 3 * year + 5 * b + 5) % 7);
    if(c == 0 && a > 11 && m >= 0.89772376543210 )
        Mar++;
    else if(c == 1 && a > 6 && m >= 0.63287037037037)
        Mar += 2;
    else if(c == 2 || c == 4 || c == 6)
        Mar++;

    Mar += Math.floor((year - 3760) / 100) - Math.floor((year - 3760) / 400) - 2;
    return Mar;
}

function leap(y) {
    return ((y % 400 == 0) || (y % 100 != 0 && y % 4 == 0));
}

function civMonthLength(month, year) {
    if(month == 2)
        return 28 + leap(year);
    else if(month == 4 || month == 6 || month == 9 || month == 11)
       return 30;
    else
        return 31;
}

function civ2heb(day, month, year) {
    var d = day;
    var    m = month;
    var y = year;
    var hy;
    var pesach;
    var anchor;
    var adarType;

    m -= 2;
    if (m <= 0) { // Jan or Feb
        m += 12;
        y -= 1;
    }

    d += Math.floor(7 * m / 12 + 30 * (m - 1)); // day in March
    hy = y + 3760;    // get Hebrew year
    pesach = Gauss(hy);
    if (d <= pesach - 15) { // before 1 Nisan
        anchor = pesach;
        d += 365;
        if(leap(y))
            d++;
        y -= 1;
        hy -= 1;
        pesach = Gauss(hy);
    }
    else
        anchor = Gauss(hy + 1);

    d -= pesach - 15;
    anchor -= pesach - 12;
    y++;
    if(leap(y))
        anchor++;

    for(m = 0; m < 11; m++) {
        var days;
        if(m == 7 && anchor % 30 == 2)
            days = 30; // Cheshvan
        else if(m == 8 && anchor % 30 == 0)
            days = 29; // Kislev
        else
            days = 30 - m % 2;
        if(d <= days)
            break;
        d -= days;
    }

    adarType = 0;            // plain old Adar
    if (m == 11 && anchor >= 30) {
        if (d > 30) {
            adarType = 2;    // Adar 2
            d -= 30;
        }
        else
            adarType = 1;    // Adar 1
    }

    if(m >= 6)        // Tishrei or after?
        hy++;        // then bump up year

    if(m == 11)            // Adar?
        m += adarType;    // adjust for Adars

    return (d + ' ' + m + ' ' + hy);
}


function Easter(Y) {
    // based on the algorithm of Oudin
    var C = Math.floor(Y / 100);
    var N = Y - 19 * Math.floor(Y / 19);
    var K = Math.floor((C - 17) / 25);
    var I = C - Math.floor(C / 4) - Math.floor((C - K) / 3) + 19 * N + 15;
    I = I - 30*Math.floor((I / 30));
    I = I - Math.floor(I / 28) * (1 - Math.floor(I / 28) * Math.floor(29 / (I + 1)) * Math.floor((21 - N) / 11));
    var J = Y + Math.floor(Y / 4) + I + 2 - C + Math.floor(C / 4);
    J = J - 7 * Math.floor(J / 7);
    var L = I - J;
    var M = 3 + Math.floor((L + 40) / 44);
    var D = L + 28 - 31 * Math.floor(M / 4);

    var ret = new Object();
    ret[1] = M;
    ret[2] = D;
    return ret;
}

function DOW(day,month,year) {
    var a = Math.floor((14 - month)/12);
    var y = year - a;
    var m = month + 12*a - 2;
    var d = (day + y + Math.floor(y/4) - Math.floor(y/100) +
            Math.floor(y/400) + Math.floor((31*m)/12)) % 7;
    return d + 1;
}

function NthDOW(nth,weekday,month,year) {
    if (nth > 0)
        return (nth - 1) * 7 + 1 + (7 + weekday - DOW((nth - 1) * 7 + 1, month, year)) % 7;
    var days = civMonthLength(month, year);
    return days - (DOW(days, month, year) - weekday + 7) % 7;
}

function holidays(cday, cmonth, cyear) {
    // American civil holidays and some major religious holiday
    if (cmonth == 1 && cday == 1)
        return "New Year's Day";
    else if (cmonth == 2 && cday == 12)
        return "Lincoln's Birthday";
    else if (cmonth == 2 && cday == 14)
        return "Valentine's Day";
    else if (cmonth == 2 && cday == NthDOW(3, 2, 2, cyear))
        return "President's Day";
    else if (cmonth == 3 && cday == 17)
        return "St. Patrick's Day";
    else if (cmonth == 3 || cmonth == 4) {
        var e = Easter(cyear);
        if (cmonth == e[1] && cday == e[2])
            return "Easter";
    }
    else if (cmonth == 5 && cday == NthDOW(2, 1, 5, cyear))
        return "Mother's Day";
    else if (cmonth == 5 && cday == NthDOW(3, 7, 5, cyear))
        return "Armed Forces Day";
    else if (cmonth == 5 && cday == NthDOW(0, 2, 5, cyear))
        return "Memorial Day";
    else if (cmonth == 6 && cday == 14)
        return "Flag Day";
    else if (cmonth == 6 && cday == NthDOW(3, 1, 6, cyear))
        return "Father's Day";
    else if (cmonth == 7 && cday == 4)
        return "Independence Day";
    else if (cmonth == 9 && cday == NthDOW(1, 2, 9, cyear))
        return "Labor Day";
    else if (cmonth == 10 && cday == NthDOW(2, 2, 10, cyear))
        return "Columbus Day";
    else if (cmonth == 10 && cday == 31)
        return "Halloween";
    else if (cmonth == 11 && cday == 11)
        return "Veterans' Day";
    else if (cmonth == 11 && cday == NthDOW(4, 5, 11, cyear))
        return "Thanksgiving";
    else if (cmonth == 12 && cday == 25)
        return "Christmas";

    return "";
}

function moadim(cday, cmonth, cyear, hday, hmonth, dow) {
    if(hmonth == 6) {
        if(hday == 1 || hday == 2)
            return "Rosh Hashana"
        else if(hday == 3 && dow != 7)
            return "Fast of Gedalia";
        else if(hday == 4 && dow == 1)
            return "Fast of Gedalia";
        else if(hday == 10)
            return "Yom Kippur"
        else if(hday >= 15 && hday <= 22)
            return "Sukkot"
        else if(hday == 23)
            return "Sukkot (d)"
    }
    else if(hmonth == 8) {
        if(hday >= 25)
            return "Chanukkah"
    }
    else if(hmonth == 9) {
        if(hday <= 2) {
            return "Chanukkah"
        }
        else if(hday == 3) {
            // Kislev can be malei or chaser
            if(cday == 1) {
                cday = 29;
                cmonth = 11;
            }
            else if(cday == 2) {
                cday = 30;
                cmonth = 11;
            }
            else
                cday -= 3;
            var hdate = civ2heb(cday, cmonth, cyear);
            hd = eval(hdate.substring(0, hdate.indexOf(' ')));
            if(hd == 29)
                return "Chanukkah"
        }
        else if(hday == 10)
            return "Fast of Tevet"
    }
    else if(hmonth == 10) {
        if(hday==15)
            return "Tu b'Shvat"
    }
    else if(hmonth == 11 || hmonth == 13) {
        if(hday == 11 && dow == 5)
            return "Taanit Esther"
        else if(hday == 13 && dow != 7)
            return "Taanit Esther"
        else if(hday == 14)
            return "Purim"
        else if(hday == 15)
            return "Shushan Purim"
    }
    else if(hmonth == 0) {

        if(hday == 12 && dow == 5)
            return "Taanit Bechorot"
        else if(hday == 14 && dow != 7)
            return "Taanit Bechorot"
        else if(hday >= 15 && hday <= 21)
            return "Pesach"
        else if(hday == 22)
            return "Pesach (d)"
    }
    else if(hmonth == 1) {
        if(hday == 3 && dow == 5)
            return "Yom Ha'Atzmaut"
        else if(hday == 4 && dow == 5)
            return "Yom Ha'Atzmaut"
        else if(hday == 5 && dow != 6 && dow != 7)
            return "Yom Ha'Atzmaut"
        if(hday == 14)
            return "Pesah sheni"
        else if(hday == 18)
            return "Lag B'Omer"
        if(hday == 28)
            return "Yom Yerushalayim"
    }
    else if(hmonth == 2) {
        if(hday == 6)
            return "Shavuot"
        else if(hday == 7)
            return "Shavuot (d)"
    }
    else if(hmonth == 3) {
        if(hday == 17 && dow != 7)
            return "Fast of Tammuz"
        if(hday == 18 && dow == 1)
            return "Fast of Tammuz"
    }
    else if(hmonth == 4) {
        if(hday == 9 && dow != 7)
            return "Tisha B'Av"
        if(hday == 10 && dow == 1)
            return "Tisha B'Av"
        if(hday == 15)
            return "Tu B'Av"
    }

    return "";
}