Do people sell board games to each other at this? I have a never opened copy of To Many Bones: Undertow and am never going to play it. Saw it was being played here and thought someone would want to get their hands on it.

Check some of the other threads for info on the auction.  I don’t know if they have a general sell/buy location other than that.

There's also the Math Trade if you want to exchange for a different game instead of cash.

Awesome, thank you.

Where is this Math trade? 

I want to hate the Math Trade because I so truly cherish the Auction, but clearly there is no shortage of items at the Auction, given I have probably only seen them wrap up a section early about once a year for as long as I have been going.  So I should just accept it is clearly a nice alternative to the formality of watching a goofy person encourage a crowd to pay a fair price for your games.  :)