My brother has a T-Mobile Touch, and there's an app which allows the touch screen to be a mouse for his comp which sounded pretty cool. <Don't yell at me, I didn't search the market for it yet...>
At any rate, when we get together for Thanksgiving at the folks tomorrow he's going to show me some of his favorite apps (since he's had more time with his phone) and I'm hoping to walk-away even that more knowledgable / up on what's out there.