We have all heard of them, whether they meet at the local Carpenter's Union Hall on Thursday nights, or it's a fraternity that is more focused on networking instead of partying, some Alumni groups, or even some Boards of Directors. When I was in undergrad, my particular school had a deep networking system in and after school which in the Bay Area was dubbed "The Mafia". This was mostly due to fellow grads hiring each other in very large numbers. Most corporations here in the Bay Area either have a Chairman, CEO, CFO, or CIO from the mafia. I never found this to my taste, so I stayed out.