Codex,
Another plug for the RAAF_Squad that Recon mentioned. Although we identify as a South Pacific P40 Aussie Sqn we don't always fly that theatre or as allies. Any theatre is fair game during our squad nights and more often than not we fly inter-squad matches. So you get a chance to fly both sides.
Currently Tues is our "Cliffs" evening, nominally from 2030hrs, although some members report in earlier. As Recon mentioned, the ATAG server and the ATAG TS. Thanks to the kind folks at ATAG we have our own TS directories. Download TeamSpeak3 (TS). Goto Multiplayer, Client, select the ATAG Hyperlobby and say hello!
If you particularly want an axis flavour I understand that JG53
http://www.iijg53.com/
have an oceania squadron.