Well, when I was at Cisco there were a lot of ways of meeting new (and interesting?) employees.

Many employees kept internal blogs on things they were working on (including CEO Chambers). Employees also had keywords for things they liked to do or were good at (C#, starcraft, hiking, investing, etc would be someone's keywords). There were also a lot of mailing lists to search to find people who liked to do things together (pythonistas, bxb-cycling, bikers, etc)

Other than that there was simply reputation (this is the 'filtering other people's opinions' bit). J.C., for instance, was known around the office as being a hilarious guy and just great to talk to. S.D. knew everything in the world about firewalls. D.C. was a great artist, yada yada...

I guess it really depends on how your company is set up and how comfortable you are approaching people.