The Hutterites have been living communally for about 400 years (I think), and have evolved an ideal size for a "colony" of about 90 people. At about 110 they start getting ready to "hive off". Colonies have been very successful, often pissing off the less organized (and less successful) locals.

http://www.hutterites.org/day-to-day/structure/

http://en.wikipedia.org/wiki/Hutterite

While similar in ways to Amish, Hutterites rather like new technology and put it to good use on their farms.