Source: http://lifehacker.com/5607031/online+convert-converts-audio-video-images-and-more
Converting WAV to MP3 or PNG to JPG is old hat for just about every web-based converter out there. Where Online-ConVert really shines is the inclusion of lesser used formats. The video converter, for example, even supports conversion to video formated for playback on the Nintendo DS—if you didn't know you could play video on your DS make sure to check out how to hack your DS for backups and supercharge it with homebrew software to see all the other cool things it can do.
In addition to supporting a huge range of format conversions Online-ConVert has a bunch of little features that make it a pleasure to use—despite it's initially clunky looking interface. Online-ConVert supports both file upload and URLs—we had no problem using YouTube URLs to create videos to dump onto our Nintendo DS, for example. Each conversion also generates a QR code that you can scan with your cell phone to download the file. Let's say you're at a computer and you don't have an appropriate sync cable or syncing software for your phone. You can convert the file and scan the QR code to initiate the download right to your phone.
Visit the link below to try out the converter or sound off in the comments with your favorite conversion tools.