Up until a couple days ago I would have listed Facebook as one of my top 3, but not anymore, not since I found Focus For Facebook. What it does is filter out all the annoying spam you don't want to read. I mean, I love my friends, but some of them do that Farmville thing, and as much as I love you, I really don't care that you found a lonely colt wandering on your farm, you know? Especially when there's like, 20 of those kind of 'updates' everyday. FfF filters all that stuff out and only posts "real" posts. It's fantastic.
Grocery IQ - best shopping list app there is, period.
Knocking Live - send LIVE, streaming video to any iphone, any generation, even ipod touch. Is the video quality as good as Facetime - no, but it's not bad, and it works over 3G
For ppl posting in this thread, instead of just naming the app, could you tell a bit about it? Thanks
eta: Knocking Live also works on some non-iphone phones, I forget which ones, but they're listed on the app's site.