The fellow running the Ars Ludi blog seems to have some good things to say regarding RPGs. Here's an article about using Backdrop Plots in your role-playing game. And here's a series about a sandbox campaign, where, interestingly, the players were required to do all the scheduling:

http://arsludi.lamemage.com/index.php/78/grand-experiments-west-marches/

What I like about  that idea is that the fellow describes how to set up a gaming campaign that is just full of stuff to do, but leave what to do and when to do it entirely up to the players...so that instead of a group of people gathering regulalry to play whatever the GM has planned, the players must garner interest in exploring, say, "the ruined abbey on the west hills" and get enough people to show up for that.