I signed up for Twitter today to get Delicious Library.
If enough people buy this, I get Boinx, which I'd kind of like to have.
It's a gimmick, their billing system was horrid on 3/26 and screwed up my order for days, I'm frustrated with them, but you still might be interested in this.
This is a referral for me to get more free software. Please use the link to get there if you purchase.