Handcent SMS
Enhanced E-mail (only fking email client i found that works the way its supposed to)
Swype - does not come native on the thunderbolt had to install beta.. LOVE IT.
Word Free
FB App
Angry Birds
DropBox (lets you transfer files between your phone and computer quick and simple drag and drop and it sync's)
Pocket Cloud by wyse (cuz im a geek and need to loginto my computer at work ocasionally)
Winamp for my music
and the usual google assortment, maps, latitude, my tracks