black rock city (outdoors, 10k's of people, 1's of mi diameter)
cruise ship (indoors, 1k's of people, 1's of mi diameter)
hiking or mountain climbing (outdoors, hilly terrain, 10's of people, 10's of mi diameter)
villages in undeveloped countries (~outdoors, 100's of people, 1's of mi diameter, occasional busses to larger cities which could carry messages back and forth)
disaster response in areas where infrastructure is destroyed (outdoors, 10's of people, 1's of mi diameter, could be a central internet link)
military (dunno..., could be a central Internet link)
this list might not be exhaustive or inclusive enough
this list might not be exhaustive or inclusive enough