Aish Hatorah
http://www.aish.com/purimmultimedia/purimmultimediadefault/Purim_Songs.asp

Hebrew Songs: Purim songs in transliterated Hebrew, with translation
http://www.hebrewsongs.com/purim.htm

The J Site
http://www.j.co.il/songs/songs.asp?id=012
[or go to www.j.co.il>Songbook Categories> Holidays-Purim ]

Ohr Somayach
http://www.ohr.org.il/audio/ra/perlman/pursongs.htm
Double index of traditional Hebrew and Yiddish songs in Hebrew
with English translation; downloadable song files in ram;
streamed audio in Real One;  full Megillah reading in ram;
doc and pdf downloads for song texts

Zemerl
http://campuscgi.princeton.edu/~klez/zemerl/display.pl?subcategory=Purim
Yiddish, English parodies, Hebrew songs (Transliteration or original text; some ram files)

Hebrew only

Jewish Agency for Israel, Education Department

http://www.jafi.org.il/education/ivrit/corner/purim/28.htm
Shoshanat Yaakov 

Chagim Institute

http://www.chagim.org.il/pur60.html
Hebrew words, 17 songs [Purim fun]

Orianit, Negev College

http://www.orianit.edu-negev.gov.il/irisshap/sites/homepage/irisi/purimkatan.htm
Songs with audio files

Amit Schools: 12 songs
http://www.amit.org.il/yesodi/hagim/purim/songs.html

Golda Meir School: 9 songs, graphic layout
http://www.tzafonet.org.il/kehil/school_tzafonet/goldameir/purim%20songs.htm

Hebrew University & National Library: Piyutim from different countries;
Megillah in streamed audio or mp3 downloads
http://jnul.huji.ac.il/dl/music/purim/purim.html 

Israel Music: 30 Purim music disks, with online clips, including the
Budapest Megillah [Hebrew & Yiddish]