As social networking goes, I am not all that active on LinkedIn, although I check in every once in a while. It appears that there are many popular domain name related groups on LinkedIn, and some of them boast hundreds of members.
Discussions in domain name groups range from issues related to domain names, domain name sales, gTLD expansion, domain name management, auctions, and pretty much everything else in between. Some of the groups are private and need special approval to become a member, and others are fairly open.
When you sign up for a LinkedIn group, you will most likely receive emails linking to recent discussions and threads from each group. You’ll most likely want to edit your privacy functionality to limit the number of emails you receive on a daily basis. I would personally probably block those emails, but that’s me because I get so many emails in the morning (To block Group Emails, go to Email Preferences —-> Set the frequency of group digest emails)
Anyway, here are ten of the most active domain name related LinkedIn groups (Keep in mind some of these are specifically targeted groups, ie European domain investors only):