Some friends of mine have been hard at work on a social music app called ;MixApp for...a good long time now. They've recently made the jump from desktop clients to a completely in-browser experience. This makes it a lot easier for new users to get started with it.
Since the new UI is all-HTML, it means I can mess around with it using javascript bookmarklets. If you're a mixapp user and you want a "mini" desktop player, just drag this link to your bookmarks bar. When you're logged into MixApp and click it, the player will minimise.
Mixapp Miniplayer