Not too long ago, BetaPlayer became The Core Pocket Media Player (or TCPMP). At first, only a Palm OS build was made available, although all that has changed since you can now also get your hands on a functional Windows Mobile build (Pocket PC and Smartphone). This popular open-source media player will allow you to play all sorts of audio and video files (the file compatibility list can be found
here), which is great if you've been searching for an all-in-one mobile media player. It looks and feels just like the old BetaPlayer, so you won't have to get used to a new interface all over again. Best of all, TCPMP is free, and can be downloaded from
here.