(Excerpts of) the Linux source code printed on a poster you can hang on your wall. Not one sale to date.

It's a niche market, and I haven't found a successful marketing strategy yet. (I donated one to the local LUG's raffle, and a couple people fought over it ... but apparently nobody wanted to pay actual money for it.)

When November rolls around, and people are starting to think about buying Christmas presents, I might go buy some Google ads.