Well I've made a few mods for these games, only release one of them but I think we should have a file hosting place for them and a whole section!
Stranded 2: http://www.unrealsoftware.de/game_stranded2.php OR http://www.strandedonline.de/
Clonk series: http://clonk.de/
Garry's Mod: http://www.garrysmod.com/ OR http://www.garrysmod.org/ OR http://store.steampowered.com/app/4000/
You should all give these a try. By the way I am not german, I'm american.