Still love my Moto Droid, not really any problems with it. Battery life isn't that bad compared to my wife's Eris. Task killer is an absolute MUST. You gotta turn things off!!
Other than that, some of my favorites are the Nav stuff, Aldiko book reader (Kindle app just came out, too), ebuddy, evernote, Gdocs, Google Skymap, Layar, Mini Info, MotoTorch LED, My Tracks, Ringdroid, twitter, and weatherbug.