Initially only available for iPad, you can now pick up VLC for any iOS device and watch all the video formats Apple doesn't natively support.
With so many popular media formats unsupported in iOS, VLC Media Player is such a necessary addition to the App Store. The latest update rounds out support for all iOS devices. We've taken a look at VLC's performance, and you can expect the same limitations on the current generation iPhone and iPod touch, but even if performance isn't always perfect, VLC is free and still a very helpful, handy app.
VLC Media Player [iTunes App Store]