This past Monday, some friends and I got together and played d20 Future… Over the online!
It was amazing. We used Skype to talk to each other (though, we are looking for a better solution — Skype only allows five connections at once). This let us communicate at a decent speed, unlike chatting over IRC or some such.
We used Gametable, a neat little utility that shares a game board among all players. You can draw on it, move icons around its surface, and chat. Being able to move tokens and draw gave a nice simulation of a game board, and the chat box was a great place to keep out of game comments and such. When someone isn’t currently involved in the game, there is a tendency to make wise-cracks. The chatbox provided a nice non-disruptive way to do so. You can even make your own icons for your character and it pushes the icon to the other players so they can see it too. I really do recommend this program.
The combination of voice chat and a shared drawing space really made it feel like everyone was there. There were even advantages to real-life play in that private conversations were a lot easier.