They are free and yet have a lot to offer...
Zamzar is a free and all-inclusive (video, music, images, documents) online file converter. In 4 quick steps you can convert almost anything to anything else; (1) simply enter a file you want to convert by pointing to its location on your local drive or address on the web(ex; youtube video), (2) select output format(eg. PDF, doc, 3GP mobile, iPod, PSP...), (3) enter email address where it should send converted file and (4) convert it.
Special features:
- provides browser bookmarklet(Firefox, IE) which lets you convert and save files from any webpage.
- convert and save any video while you are watching it(supports Youtube, GoogleVideo, Myspace, Revver, PutFile, Break.com, Apple, Trailers, Dailymotion, Metacafe, iFilm, Grouper, Blip.tv)
- file size can't exceed 100 MB
[NO LONGER WORKS] Media-Convert
Media-Convert also lets you convert all types of files, i.e. video, music, images, docs and archives. It's also free and supports almost all conceivable file formats. Procedure is pretty much the same; select the file, specify output format and let it do the rest. Once it's done with a file, it will provide you with a link from where it can be downloaded.
Special features:
- each converted file remains accessible for 6 more days, so if you want to share it with friends you can forward them a link to download page.
- input file format auto-detection(no need to specify input format)
- additional option to adjust conversion settings(like fps, bitrate, codec, audio rate, etc..)
- download file directly to your mobile via WAP or GPRS.
- file size can't exceed 150 MB
Mux [No Longer Available]
Mux lets you convert youtube and googlevideo videos to following formats; mpeg-4, Quicktime, iPod(m4v), flash video, windows media, mpeg-1/2, windows avi, 3gb mobile and OGG Theora. It's not as powerful as above mentioned zamzar or media-convert however it has some handy features that you won't find with others (see below).
Special features;
- for more demanding users there is a power mux which allows users set additional settings on output file(bitrate, fps, file length...etc).
- there is also a mux mobile [No Longer Available] which lets you convert web-videos to mobile format(3GP, AMR) and instantly forward them to any mobile for free.