I think everybody knows the ladders on Clanbase. They provide us with European 2v2, 3v3, 5v5 and 6v6 ladders. Next to these European ladders, they have a 3v3 and 6v6 ladder for Polish clans, a 6v6 ladder for English clans and a 3v3 ladder for clans from the Benelux.
http://clanbase.ggl.com/ladders.php?gid=25
http://clanbase.ggl.com/ladders.php?gid=25