I really have no idea why there's so many time tracking apps for the mac. But, I'm not claiming to be an expert, because if I were to test drive every last one, I wouldn't be able to make an informed decision until 2009.

That said, I've used a few, and I like Timebox the best. It's very simple, while still packing many features. It handles multiple projects very well, and makes it easy to switch between them. It generates nice, clean reports, and can also export them to be fed into a database. And, while I haven't used it's web feature yet, it's nice to know I can, if need be.

In short, it works for me. And, works pretty well. Chances are, it'll probably work for you too. You can go ahead and explore the 200 other options out there. But personally, I'm stopping here.