The Core Pocket Media Player (TCPMP) is an open-source media player for Palm OS- and Windows Mobile-based devices. Version 0.66 was just released and the list of changes (http://tcpmp.corecodec.org/changelog) is truly impressive! To make it short: TCPMP is the only media player you'll ever need to install on your PDA! It includes video support for DivX, XviD, MP4, WMV, and audio support for MP3, AAC, Ogg, AC3 and much more.

Download link (http://tcpmp.corecodec.org/download)