Welcome, and I hope you enjoy your stay here in the Android Forums!
Widgetsoid - if you're looking for ballin' widget wise? this is it.
Ultimath - yes I know, my application, but IMO if you're still in school, at most levels, this can still be a quite handy tool, having frequent updates up until now, next update is planned to be a major over haul
Launcher Pro - Pretty good home replacement screen, cant remember the name of my other favorite at the moment
Swype - epic sliding keyboard, slide your fingers across all of the letters and it forms the word your looking for most of the time, hard to explain, check it out (you may not be able to get this one though, I'm not sure if its out of beta)
MotoTorch LED - turns your phone into a flashlight (includes widget)
Handcent SMS - replacement messenger, feature packed
EasyTether - turn your phone into mobile internet for your laptop (free version only allows non-secure sites, while paid is a one time fee that allows you onto secure ie Gmail Facebook Paypal etc)
Angry Birds - most addicting game I've ever seen
AppBrain App Market - sub app market (along side normal) suggests applications you may like and shows you the most popular/best (opinionated) applications, I find it more than extremely useful
Hope this helps
