Ukulele Lessons and Song Collections
Chordseasy (awesome website that is searchable, transposable, and in the compressed format I like)
Alligator Boogaloo (lots of compressed tabs--chords and lyrics on same line--the format I prefer)
Richard G's Ukulele Songbook (more compressed tabs--chords on some line format).
Ukulele Hunt (a lot of lessons and songs)
Ukulele Dave (includes tabs and music for WS64's reduction of "The Good, The Bad, and the Ugly")
Live Ukulele (includes tabs for Guava Jam)
Beatles Ukulele Songs (no sheet music, but visual/audio demonstration of lots of songs)
Ukulizer (this site has a lot of cool functionality Ø;).
General Music Lessons
Uke Skywalker and Tuba Fett (I didn't know about these guys till after I created this site, but how I could I not link to them.)