Tweetie/Twitterriffic/TweetDeck - they're better than 0.x Mauku
Air Sharing - Sharing via wifi
Evernote
Bloomberg - better than a web app by far for stocks
1Password - combined with the desktop app, works great for storing passwords
AroundMe/Priceless Picks/WHERE - location aware way to know what's around you
Convertbot - I cannot live without this conversion app
TransMate - language translation that's fast... reminds me of how badly my German has gotten
Trapster - location aware app that has a public sourced/input backend telling you where cops hideout. Seriously underrated, saves me tickets.
Layers - it outputs Photoshop files *.psd's man... seriously!

And of course... the popular games. I'm knee deep in Unity3D development lately, so that has my attention, Papervision3D (for Flash... which is useless on the iPhone prior) and stuff like that.

That's my list. There's a few others I'd list, but they're inevitably going to be duplicated - Maps, multi-IM client, Skype... that kind of stuff.