I'm a member of a mastermind, and spend most days in a Campfire room with fellow bootstrappers.
I work from home and don't have coworkers. Being able to have immediate access to really smart people who complement you is pretty much one of the best things that have happened to my business this year.
- Matt Goldman
But starting a Mastermind group is easy: find some friends who are in a similar position to you, and propose that you formally meet once a week. If you're local — great! Show up at a coffee shop. If you're remote, get on a Google Hangout.
The other is online and focused on WordPress products (plugins and SaaS services). We meet about every month and we'll see each other in person at a conference in October.
Both are pretty small right now (3 of us in each), but we'd probably do 4 if another person fit in.
I started up the 2nd because of the focus on WordPress and a little more frequency of connecting with like-minded entrepreneurs.
I like the idea of more regular spontaneous chats on hangouts or campfire though, especially if guys like bdunn and patio11 are doing it.
We have 6 members so far; I think we'll cap it at 12.