Rhapsody (my online music provider of choice) has continued to make improvements to their online, browser based version of their music player.  The most recent addition is support for the "My Library" feature that's long been present in their desktop player.  You can add albums or songs to your library for future recall, rather than having to search for them again, and just like in the desktop client, it's portable across machines.

Since I've had nothing but trouble with their desktop client lately, this makes the online version a lot more attractive.  It works in Firefox, and supposedly even under Linux, which is pretty sweet.  $25 bucks a quarter, zillions of albums, and works anywhere there's a 'net connection.  Can't beat that.