GIStribe is a social network that is also a great resource for GIS users. Details are below for those interested in participating in a weekly chat.
What: GIS Chat on Twitter with #GIStribe
A social network of GIS geeks, ninjas, students, teachers, entrepreneurs, and professionals
When: Wednesdays at 3pm EDT / 12 pm PDT
Where: Hosted on Twitter using the hashtag #GIStribe
Who: People from all over the world interested in GIS
Click here for more details including how to join the Twitter chat