I'm surprised that so many people here are saying that pure-CSS buttons are actually a good thing, because they're programmatic. Sure, they're programmatic, but the code behind them is really confusing. I'd much prefer to use a sane drawing environment like an HTML5 canvas or the Raphaël library. Raphaël is perfectly suited to this sort of thing. Anything you make in Illustrator, you can make with Raphaël, and you get nice, clean code.