Video Monkey allows you to convert video between a variety of formats and is based on the now defunct Video Hub application.
It's is a comprehensive video converter that lets you convert video files between several different formats very easily. Video Monkey provides presets for all of Apple's most popular devices including iPhone, iPod and Apple TV. Other standards it converts to are DV, DVD, Tivo and all the major video formats including AVI, MP4 and Quicktime formats. The interface allows you to drag and drop multiple videos in for conversion and adjust the bitrate, frame size, frame rate and audio quality before you convert.
These kind of tools tend to be all very similar although I liked the fact that in Video Monkey you can get an idea of the output size before it makes the conversion (although it's only approximate). You can also preview files and you're kept updated on the progress of the conversion with a progress bar. You can also pause encoding which is useful for long conversions and you last settings are always saved.
There is little to fault with Video Monkey. It could do with supporting a wider range of formats such as DivX and Xvid but for most people's converting needs, it's more than enough.
- New version of ffmpeg, but 32 bit only