Last Summer I spent a few wonderful days on Lake Champlain and got to enjoy some time on Burton Island State Park.
See:
http://www.vtstateparks.com/pdfs/burton.pdf
In addition to day use (for a fee), the park has campsites, cabins and overnight transient boat slips (also all for a fee). It's really nice.
I have also spent time on Lake George and most of the islands on that lake are all part of a park system that allows camping and overnight docking for a fee. It's also really nice. See:
http://www.lakegeorge.com/guide/island-camping.cfm
It would be awesome to see something like this (on a smaller scale) on one of the Winnipesaukee Islands. Ragged would be ideal, IMO, since it already has docks, power, outhouses, and a building that could be converted to headquarters and a camp store. I realize it would probably never happen, but I think it would be sweet.