Perhaps every one knew this but this guys,
http://www.designmodproject.de/forum/index.php (http://www.designmodproject.de/forum/index.php)
have done three nice add-ons for North Africa, Finland and the Eastern Front. I found installation to Ostfront touchy but that's just me. Remember to click the English language icon at the site if you don't read German.
Besides not being "official" add-ons like the ones published by Slitherine, are they similar? Are they full-blown campaigns?
Very simlar and complete. See. the official add=ons are almost tactical while these are operational like the base game.