If you're into playing older wargames and can't find an opponent, then VASSAL is the way to go! Here's a short description of the application:
VASSAL is an engine for building and playing Internet-capable versions of turn-based, human-vs-human games. Players move and manipulate game pieces via the mouse while typing accompanying text. Moves can be recorded into a log file and stepped through one at a time for email play. During live Internet play, all moves and text are automatically broadcast to other players in real time. Combining a live VASSAL session with a third-party Internet voice-chat tool (such as NetMeeting or TeamSpeak) allows you to play with people around the world at very close to face-to-face pace.
You use modules to emulate the games you want to play. What I've seen looks great. They have alot of Avalon Hill titles, along with other manufacturers. But apparently they're a loss for SPI titles.