MOOP!

I have an Ars Magica group that plays Monday nights (generally). It tends to shift to the home of whomever is running that night... I'm a mile from Newton Highlands, damarie is a couple of blocks from Central, chainkill is up in Somerville (I'm not sure exactly where, as we haven't been there yet), and Logan-the-LJ-Less is a couple of blocks from Davis, so we cover a decent amount of mostly-near-the-T ground. Having a fifth player would be nifty.

I can babble at you about the wonders of the AM system, but the general highlights are:
1) Everyone has multiple characters (though the general hope is that you'll only have to be in charge of one at a given time): one mage, one beefy sort, and some number of redshirts.
2) It's claim to fame is that it has a nifty magic system (it's basically verb + noun, so "create fire" or "destroy minds" or "control animals").
3) It was held by White Wolf for many years, so it has a decent amount of that "storytelling is the important part" feel, plus it encourages players share game running duties, rather than having a single GM forever and ever.