Many people just tweak stuff themselves, I have my own edition of st hilaire and carentan with more units that u can order and if you play those maps on hard, ai throws some nasty stuff at you later in game(once you cap number of flags).
I know some people are working on custom new skirmishes with maps, but it will take time. There is also DCG for mow as thats being worked on, early version is out too on the dms forums.