I often have to do video conversion from one format to another, such as avi to flv, avi/mpg to phone and vice-versa. Some freebies I have in my toolkit are below.

DVDVideoSoft - Free Studio A very complete conversion tool box which includes the following:

Free YouTube Download

Free YouTube to MP3 Converter

Free YouTube to iPod and PSP Converter

Free YouTube to iPhone Converter

Free YouTube to DVD Converter

Free YouTube Uploader

Free Uploader for Facebook

Free Video to Android Converter

Free Video to Apple TV Converter

Free Video to BlackBerry Converter

Free Video to HTC Phones Converter

Free Video to iPad Converter

Free Video to iPod Converter

Free Video to iPhone Converter

Free Video to LG Phones Converter

Free Video to Motorola Phones Converter

Free Video to Nintendo Converter

Free Video to Nokia Phones Converter

Free Video to Samsung Phones Converter

Free Video to Sony Phones Converter

Free Video to Sony Playstation Converter

Free Video to Sony PSP Converter

Free Video to Xbox Converter

Free DVD Video Converter

Free Video to DVD Converter

Free Video to Flash Converter

Free 3GP Video converter

Free Video to MP3 Converter

Free Video to JPG Converter

Free Audio Converter

Free Audio to Flash Converter

Free DVD Video Burner

Free Disc Burner

Free Audio CD Burner

Free Audio CD to MP3 Converter

Free Screen Video Recorder

Free Image Convert and Resize

Free Video Dub

Free Audio Dub

Free Video Flip and Rotate

Free 3D Photo Maker

Free 3D Video Maker

Pazera - List of Video and Audio converters

Any Video Converter

mkvtoolnix - Recently downloaded a TV series in MKV format and it defaults to Russian language track. I use Windows Media Center for my media center computer and there is no mechanism to switch languages. Found mkvtoolnix which allows me to manage the tracks easily and quickly.

I use Format Factory one programme that converts just about anything to anything.

I use Format Factory one programme that converts just about anything to anything.

Thanks for the addition. To expand on Format Factory as it relies upon system codecs > K-Lite codec packs

On Linux I use mencoder for quick and dirty transcodes (Windows link here). Probably a bit more involved than a Windows user would like, but I'm sure that a *.bat file could be whipped up to get a whole mess of files squared away. Cool thing is that as long as your codecs are up to date, you just need to worry about the output variables. Biggest complaint I have against it is that it is not that multi-threaded.

For going dvd -> m4v/mp4/mkv(what I use for my stuff) you can't beat handbrake. X.264 is a great encoder with plenty of speed, awesome compression and more options than you can shake a stick at.

I actually downloaded the trial version (2,0) of Badaboom and fired up Windows 7 (first time in months) to check it out. Was about 2,5x faster than using handbrake, but I have a pretty anemic nvidia card (210m) in my laptop. Quality wasn't that bad for an ipod touch transcode (from a 21 GB blu-ray rip), and it ran at mid 40's FPS. Biggest issue I have with it is that it only transcodes unprotected content and dvd43 does not support 64 bit OS (except as plug-ins; which of course Badaboom doesn't support).