Copied from Wikipedia, these all support gapless playback. I can only personally vouch for the Apple stuff, though. Hope that helps. :thumbup:
* Microsoft Zune supports gapless playback with Zune 2.5 or later firmware.
* Rio Karma and TrekStor Vibez: Gapless hardware players with no software dependency
* Apple iPod classic supports gapless playback of MP3s and AACs from the fifth generation onward
* Apple iPod nano second generation and later
* Apple iPhone
* Apple iTunes 7.0 and later versions support gapless playback on Macintosh and Windows without having to combine tracks during encoding (a limitation of previous releases)
* foobar2000
* Aqualung
* MiniDisc
* ATRAC3 NW Series Sony Walkmans
* Rockbox for various digital audio players.
* Music Player Daemon for Linux and other platforms.
* Music On Console
* Archos Gmini XS202S
* Sony PlayStation Portable
* Rhythmbox