There's a fair bit of material including quicktimes, sound bites, an image gallery, a look at the actors behind the voices, episode guides and more at:

http://www.redwall.tv

It's not the official Redwall cartoon site (which would be http://www.redwalltv.com), but is a bit more extensive than theirs, and will hopefully be undergoing some updates fairly shortly as respects downloads of production art, Nelvana text docs, multimedia stuff - and a bit more material on the original series.

chance (the official site seems to be eternally stuck in 2001, and those responsible warn me not to expect much by way of updates. Ever.)