I know of a few:
Cleaner (
http://www.media100.com )can create mpeg 1 and 2, but the output is pretty basic unless you get its charger (software) or supercharger (hardware) enhancement packs.
I use charger, which lets me customize my settings ad infinitum. Cleaner is not a cheap encoder, nor is it a fast encoder -- and from what other message boards suggest, Media 100 (the current owner) is letting the program languish.
Other solutions:
Heuris (
http://www.heuris.com ) makes an encoding solution that I think came bundled with Query's VCD authoring solution (which may be defunct now), and it seems to offer much of the customization of Cleaner/charger, but focusing solely on MPEG. I don't know anything more about this product.
Digigami (
http://www.digigami.com ) has an mpeg encoder that I don't know anything about also.
There is a freeware solution called Movie2MPEG (
http://www.versiontracker.com/morein...id=3013&db=mac ) but last time I tried this work-in-progress it was still pretty buggy.
Last, you could install Virtual PC and use one of the many freeware PC encoders, like TMPG, that can be customized to an extent that puts cleaner/charger to shame (and did I mention its free) Despite running on emulation, the speed is pretty reasonable -- which frustrates me to know end when I think what I paid for Cleaner/charger.
With MacOS X, it will probably be much easier to port a lot of these freeware solutions to the mac, so stay tuned to this. The VCD helper site (
http://www.vcdhelper.com ) has a Mac forum where mpeg related topics pretty much dominate, so you might want to check there too.
Hope this helps.