There have been several shows on IT Conversations lately that I've really enjoyed, but failed to mention on my blog. One of those talks was Christopher Allen's talk from Mesh Forum on the Dunbar number. The Dunbar number is a measure of the cognitive limit to the number of individuals with whom a person can maintain stable relationships. Christopher talks about how the number is often misused and what the real limits are in various contexts. Christopher has slides and other posts on this topic at his blog, Life with Alacrity.