From HCI Design:
Lean CD is a full featured CD player that uses minimal screen space. Stick it in the titlebar of your favorite app and have instant access to your CDs. LeanCD supports all the standard controls, such as pause, resume, and eject, plus you can seek to any point within a track (either instantly or in 5 second increments). All this functionally (and more) plus the current playback location is packed into a compact 138X16 pixel window.