Grooveshark not only has a cool design, but is an interesting service as well. It lets you search for music and play it, streaming through the Flash player. Artists can submit their music directly to Grooveshark, giving them a promotional platform, as well as monetary compensation.
Anyway, to the design.
Simple, visually interesting, and functional. It also has one of those big, in your face search boxes that are in vogue with “Web 2.0″ sites. The front page has a Google-esque simplicity that leaves no doubt what your next step should be: to search.
When you perform a search, you are taken to the following screen, which serves as a results page and portal to play songs or perform other actions. (You can also add songs to the queue to be played, get Flash embed code to put songs on a website, share songs, etc.)
The results page is displayed as a nifty iPod-style menu, easily sortable by Songs, Artists, Albums, or Genres. You can drill down through the menus to peruse the available tracks.
The breadcrumbs and still-accessible search bar are nice touches.
The styling strikes me as slightly Mac-like, but not quite. The interface seems fairly polished, and easy enough to navigate. Pretty good overall.