That's a pretty cool map info site AcE :)
I've just been checking it out, learned a couple of new things, and will be back when i'm trying to incorporate some of it in to my trickjump map which is half-built.
There are quite a few good mapping websites, but it seems you get some gems of good info from each one rather than there being one complete source.
modsonline is definately a good mapping info site, so with that already mentioned, and in no particular order, I like:
Surface
map-center
Splash Damage
Tram Design
Jolt Mapping forums (no longer a fully active mapping forum but some good info still in there)
Map-Craft - nice helpful ppl and some very good tutorials which are helping me get my map in to shape
Good luck with it. :)