Some highlights that I think are worth mentioning, I'm missing a LOT of people here: :/

ag2 and http://nitapps.com/
fanoush and his initfs/kernel work
fiferboy and his UI enhancements
Jaffa/aflegg and mediautils/770Flasher
Johnx and Debian
Krisse and the Internet Table School
Milhouse and his work on bugzilla/SD booting (he's getting a t-shirt, so he's probably covered )
Penguinbait and KDE

I'll append some more if I remember any particularly glaring omissions, but it's at least a start.