From TMB Wiki
A very, very extensive listing of Media Players and their advantages, features and disadvantages is on the wikipedia: Comparison of Media Players!.
Links to some of the most interesting players (homepages)!
Apollo 37, Beep Media Player, foobar2k, VLC, WHAMB, Winamp, X Multimedia System, XMMS2, Audacious, Media Player Classic, J-River Media Cnter, All-In-One MPlayer, Songbird, Unix Amiga Delitracker Emulator, KMPlayer, MediaMonkey.
For more detailed discussions/descriptions on some of these players see the listing below.