In late December 2011/early January 2012 I used my meager bonus to pay off my small credit card balance and the remainder on my car loan. Since then I've made it a point to keep ahead of my CC balance. So, not only did I not pay any interest, I got ~$300 in cash rebates, which gets deposited straight to my account.
FWIW, my FICO score was ~15pts lower when I refi'd this summer; I wonder if this had anything to do with it. I only closed one account this year - my car loan, and I had looked into doing a refi in the spring, but never went through with it, so there may have been several inquiries into my credit.
