Xmms-weasel is an insanely useful plugin for the XMMS media player. Xmms-weasel allows you to dock your XMMS windows to the top of the screen, where they scroll off the desktop, save for a user defined number of pixels. When you place your cursor over the revealed window area, the entire XMMS window slides down. When the cursor leaves the XMMS window area, the window moves back up off the desktop.
Xmms-weasel is easily customizable, with overlap settings, speed, and delay. It has a few minor bugs, such as the playlist window scrolling offscreen when the menu buttons are used, and a few issues with the Metacity window manager, but is perfectly stable. It is currently in version 0.1, and can be downloaded at
http://xmms-weasel.sourceforge.net. Future versions plan to allow XMMS docking on all sides of the screen, and bugfixes.