tikl is great...like the old nextel walkie talkie. Doesn't use your minutes and you can talk to one or several at once. Kathy and I use it when shes shopping, and I'm looking at the good stuff in Costco..

panndora is great, but that's almost a given
just found nextflix for android. works good over wifi
slingbox is also excellent if you're stuck in a hotel room on the other side of the country, or on an airplane with wifi (since they block netflix)
beyondpod for automatically d/l'ing podcasts
appbrain/fast web installer so you can automatically send apps to the phone from the web browser.
bubble is a bubble level app
droid48, rpn scientific calculator
google sky map for stars is really awesome
iheartradio to listen to john and ken bash on stupid politicians even in new jersey
quick settings is a cool little app to go directly to most used settings (bluetooth, wifi, airplane mode on/off, etc)
textplus for if you are near the monthly text limit
yelp for restaurants in strange places
Don't use my phone for too many games I guess...