RP Tools, a DM's best friend.

[BizzaroStormy]

I've found that the RPTools Map Tool and Token Maker programs seem to be great for running campaigns over the internet (or LAN if you prefer a bunch of beanbag chairs to a table).

Here's a link to them. http://rptools.net/doku.php

[darkzucchini]

True story.

[LoopyZebra]

I haven't DMed using it, but found it was very easy to play using MapTools. Much better than OpenRPG.

The first tutorial here also helped.