Actually, there's a speciality multimedia called UHA. Search google for it. I don't think it's still in development, but I've seen it used by warez guys. IIRC, the program itself is free. I've seen it compress 1.3 Gig of data into 270 megs. The only catches are that it's f***ing slow and that you can't extract a single file from an archieve (ie, you have to decompress the whole thing). I usually get around that last problem by only compressing a single video file at a time.

Cheers,
cgkanchi