I've seen a few "post your IQ" or other test topics on the forums here. If people are even close to truthful with their score I would guess the average IQ would be ~125, quite possibly higher. This is far, far above the average (90-110).
The on-line IQ tests are notoriously inaccurate and I would suspect that most who post on this Board would score as average, or slightly below average on the conventional professional IQ tests.
I think we do have a poster here who is offiicially a member of MENSA, and we have hundreds here who have granted themselves this hallowed membership by online tests.
HS