In the manchester area:

Mosaic Art Collective - just opened a new space downtown

Arts Build Community - they just did a huge multi-mural project

550 Arts isn't necessarily a collaborative or collective, but I think they act like it - very community minded.

Check in with Grace at Creative Framing Solutions on Chestnut St. She and Studio Verne right next store are very involved in the arts scene.

And then the Manchester Arts Commission is looking for a passionate arts resident who might be interested on serving on the commission and doing exactly what you're looking to do.