For those that don't know it's a central site for organizing offline meetings of all types, according to where you live. I searched a few cities in my area and couldn't believe the huge number of groups that meet on a regular basis. The groups are of all kinds, but a LOT of them appear to be business-related (local biz masterminds, etc).
So if you're looking to find more offline clients or network with local businesses, go to...
Use the Internet to get off the Internet! - Meetup.com
..and punch in your zip code. I'm sure you'll find tons of potential networking opportunities in your area!