Wow. This is great! You can listen before buying. Discover new music for free, and don’t dive into the dark depths of P2P music download (not that I am really embarrassed when downloading music from people who already make a fine living out of it, but P2P mostyl means crappy-quality-and-hard-to-find music, as far as I am concerned). Tell it what artists you like and listen to these artists plus other stuff that it thinks you’ll like.
It doesn’t have a whole lot of Jazz artists (most of these days’ popular stuff makes me throw up), but the idea is really brilliant!