XviD is an MPEG-4 compatible codec, which produces very good video quality -- something that really competes with DivX.

If you're interested of trying "exciting" codecs, XviD is definately meant for you. Codec is still under heavy development, but quality-wise it is already "there" on par with big names like RV9 and DivX.

This version of the codec is built by Koepi -- there are several binary versions available, but as this seems to be the most popular one