Mac users who have wanted to share audio, video, and pictures with their Xbox 360s have had to depend on Connect360 from Nullriver Software. Now, however, there's a new option: Rivet from Cynical Peak Software. Frankly, it does about the same thing as Connect360, running in your menu bar and allowing you to share media to your Xbox 360, though it does add a few convenient features.
According to the developer, Rivet allows you to "supply multiple search paths for your media" and display your folder media folder hierarchies properly (instead of in a long, flat list). So if you've been frustrated by those limitations, Rivet is worth a look. In my brief testing it worked just about as well as Connect360.
Rivet is $18.95 and a demo is available from Cynical Peak Software.