PlayVoll's PVP120 personal video player can switch from portrait to landscape mode
Can't really think of another portable video player that does this (though plenty of PDAs can), but the 2.2-inch LCD screen on PlayVoll's new 20GB PVP120 can switch from portrait to landscape mode when you decide that it's time to stop listening to Ratatat and time to start watching a little My Big Fat Obnoxious Boss. The PVP120 is a little bulky (it's nearly an inch thick), but it does support for playback of MPEG-1,
MPEG-2, MPEG-4, VOB, AVI, DivX, and XviD video files and MP3 and WMA audio files and come with built-in speakers (we think).
[Via Akihabara News]