VASSAL

Here is something I keep meaning to look into, but never seem to have the time to actually figure it out:

The VASSAL Game Engine

VASSAL is a game engine for building and playing online adaptations of board games and card games. It allows users to play in real time over a live Internet connection (in addition to playing by email). It runs on all platforms, and is free for personal use.

This seems like just the thing for running long distance boardgames.