I agree with Lally. The former Grove Council (when such still existed) had a seperate forum which was never used. Honestly I even forgot the link myself and never logged in there for years now and I am the faction leader *coughs*
As for the rest... one hint on organizing... give a very specific timeframe where you ask if people have time for something.
In my own experience... saying "please say when you have time" ends with "I try to be there!" and won't get you anywhere. XD
Also try to make small events fitting to whatever you try to pull off there. You don't need a DM always to make some interesting things like offering classes, training and the like.
And lastly, it won't always work but try to give the people something to do to keep their interest up. A common goal is nice but people want entertainment on the way.
Edit:
P.S. I also recommend MSN mainly for the nifty group-chat function!
