Hi Skybird. Yeah they've been down for a while now ):
There's a bit of stuff for TvT and SF here:
http://www.panzersim.com/forums/index.php
Fivetide from panzersim was a mod at Lighthouse and asked them after they shut down for the stuff on their forums but got no joy.
Also useful mostly for SF is:
http://tanksim.org.ru/
but most will need to translate.
Sorry if you've already got these. As for modding SF, Steel Panzers has recently gone to v1.3 and several user missions have been posted. I and several others have also done our own missions but not posted them yet mainly I guess as it's difficult to polish them up to include all texts and in-game triggers etc. I'm not that far away from putting a few up.
Otherwise Voyd has done an excellent Dynamic Mission Generator which is discussed here:
http://www.subsim.com/radioroom/showthread.php?t=147437
I've tested it and it works a treat.