We do silent auctions at work for charities - all of the items being auctioned off are set up in our large meeting room, with a sheet attached and you just write your bid down on the list if you want to outbid the person ahead of you. Some of the bidding wars get crazy!
It's cool - some people donate pre-made things (wine is popular, so are movie passes with candy) but a handful of people make things by hand and it's fun to see what sorts of creative things my coworkers get up to.
I put a scrappy little baby/dog quilt in once and then bid $50 for it myself. I figured that made it win-win; either I'd get outbid and earn/donate more than $50 for the charity; or I'd donate $50 of my own cash and keep my quilt. If I remember correctly, the quilt ended up going for $75, which I thought was pretty good considering it was a very small & simple quilt. I wasn't sure it'd get any bids at all, so I was content. (The quilt was "free" in my mind, since it was all scraps, even the batting.)