Yesterdayland.com-- where you'll find a synopsis and a somewhat active messageboard . . .
The Xyber 9 Memorial-- another fan site, Mela seems to have more cast info than most of us here, and a few rare pieces of artwork too.
Xyber Niners-- Dalliann's Xyber 9 fansite, it still needs some work (much like this site) but it looks great so far!
And here is a link where you can get yourself a copy of all the episodes that aired in the US . . .