Michael Verdi has created this pdf takes you step-by-step through compressing video using the dual pass feature of 3ivx. Combined with MPEG4 audio, you can produce files in the 60 - 70 Kbits/sec range that look and sound pretty darn good.
Click here to download the 3ivx pdf. [ pdf ]
Note: The pdf details the steps to compress from Final Cut Pro. The process is the same if you are using QuickTime Pro for Mac or Windows.
Check out the 3ivx web site.