Here’s an online service that will transcode FLVs for you into several common formats, such as AVI/DivX, MOV/MPEG4, 3GP, etc. I’ve only had a chance to try it on a couple videos, but it seems to work well. You can submit a YouTube URL or a direct link to an FLV and it will kick out a recompressed version that you can easily play on your desktop, iPod or PSP. –Link.
They’ve also released the trasncoder source under the LGPL, which you can grab over at sourceforge and use in your own transcoding project. Nice! –Link.