Use a Mac and tired of your current browser? (or maybe just have too much time on your hands)? Apparently there are 83 or so browsers to choose from. Some of these are a bit of a stretch calling them browsers (realplayer, netNewsWire) just because they have some rudimentary HTML display capability.
Of course, all of the usual suspects are represented in the form of Netscape, Mozilla, Firefox, Camino, and Opera. There are also some interesting variants like the ‘Eric Shore Baur’ browser that in instrumented to measure page load times and allows for playback of web actions.