Dabbleboard also works... but in my experience Google docs is your best option if you trust your players not to screw everything up, and ditzie the best if you don't.

Hey, awesome sites for map making! Thanks! And that's an interesting combat system that I'll have to try out!

That is a useful tool. Thanks for sharing the link

I actually just posted this sidebar the other day to explain how I've handled PbP combat in the past games I've ran.