Web is my main use for it. I love it because it's like you reached into your computer screen and pulled the Safari window out to hold in your hands.
If you remember, the tablet was referred to as the Safari Pad back when Apple was developing it but chose to release the iPhone first. I think Safari Pad is an excellent description for its primary purpose.
That said, now that I've used Photoshop Touch on it I'm convinced that the iPad will become a powerful content creation tool soon. It's not quite there due to the limited processing power, but once they put a dual or quad core CPU inside it'll be a formidable challenger to both desktop and laptop computers.