VLC media player is a highly portable multimedia player for various audio and video formats (MPEG-1, MPEG-2, MPEG-4, DivX, mp3, ogg, etc) as well as DVDs, VCDs, and various streaming protocols.  It can also be used as a server to stream your media out to world.  It doesn’t need any external codec or program to work and I must say that it works great.

It also has many skins/themes that are free to download.  You can view all of the skins here –> VLAN Skins

There is also a portable version called, VLC Media Player Portable. It is the popular VLC media player packaged as a portable app, so you can take your audio and video files along with everything you need to play them on the go. You can place it on your USB flash drive, iPod, portable hard drive or a CD and use it on any computer, without leaving any personal information behind.