Mod DB is known place for The Witcher modders. It's very friendly site for bigger mods and adventures, they're providing comfortable system for creating and maintaning profile of: group, mod, game, engine, etc.
Through all these years we gathered nice catalog of the biggest mod and adventures there
http://www.moddb.com/games/the-witcher/mods Currently I've admin rights at TW and TW2 profiles.
http://www.moddb.com/games/the-witcher-2-assassins-of-kings It'd nice to see some activity there ;) I'm open for any ideas - there's a big space to do sth interesting with Mod DB community :)