I get use out of most of it.
The top two uses (kind of obviously) are as a phone and iPod. I use the iPod almost all of the time in the car and the phone...well duh, when people call. I love using the packaged earbuds because it's much easier to talk/hear using that. No awkward holding the phone, and it's so much louder.
I use e-mail on the phone, but it's more of a "because I can" thing. I usually look at the important ones on the MBP when I get home so I can follow a link to a video or whatever.
I also use it for a shopping list, to-do list, news (RSS, AP Mobile News, NY Times), track gas purchases and mileage, info grabber (where is this address? where's the nearest starbucks? what's the weather like?).
I also use some games on it, but I still mostly use my Wii for those. I'm about to sell my Nintendo DS, mainly because I have the portable time-wasters on here. I liked a few of the games on the DS, but if they're not time-wasters, I want really in-depth games (Zelda, Guitar Hero, Pro Evo. Soccer, Mario Kart).
So basically I use it for everything. I wish there was an app that would give me local radio stations via the Internet, but so far there isn't. There are of course little additions the device needs, but it's gotta be the best smartphone out there for what I do.