United States

Doubt this is a place to find others for such a purpose. There is 'Jamspot' (they have a few locations, one is in Wakefield) - but you pay to be hooked up with other players to jam. Look at Craigslist.

There are a ton of open mics in the Boston area, but most tend to be solo/acoustic types. Outside the city there are open jams in many places.
If you're on Facebook, do a search for Boston/Massachusetts area open mics and jams, ther eare many FB groups for these. Also check Meet Up.