You'll find most of the people who come to this site are network / system administrators. Initially a lot of the visitors were network certification aspirants (because of the quality of the networking material on the site).. so you'll find prospective Network+, MCSE, CCNA and CCNP types. Now we also seem to get a lot of administrators and network engineers.. probably because of these forums.
Honestly theres nothing better than a good forum or newsgroup for finding answers to questions you might have. Thats why a lot of them seem to post here.
You also see just general computer types -- the kinda people who are very enthusiastic or passionate about technology and networking.
As for me, I do freelance security and penetration testing work. but it doesn't earn that much of a living still.. its getting better. I've also done a stint in network administration. You can read about all the firewall.cx team members on the team page:
The Team Page