iovSoft Video Converter is a free multi-format video converter. Quite a few video converters by this company have been discontinued and incorporated into a single video converter. One of those converters is iovSoft MKV Video Converter, for example. Now, the application is absolutely free, too.
The video converter allows you to convert video files between a variety of different formats, including 3GP, AVI, MPGE-4, H.264, AVI, FLV, MKV, etc. It also supports quite a few audio formats and it has conversion profiles for a variety of different devices, such as iPhones, iPods, PSP, Playstation 3, Xbox 360, etc.
Graphically, the application doesn't look impressive, but it is still usable. It has a built-in video player that does an OK job of playing video and quite a few conversion profiles.
In terms of performance, this converter does a good job of converting files between several formats. I tested it with an MKV and an AVI file, and I didn't experience any problems with either of them. The app was also on par with other converters in terms of speed. As far as quality goes, don't expect it to produce top-notch files. But if you just want to play some files on your mobile phone, iovSoft Video Converter probably will get the job done alright.