These are so cool! They are called Perfect Pushup and you can get them in a lot of places. I picked these up at Wal-Mart for about $20.
What they basically do is allow your arms to rotate while doing push ups. Now...that may not seem like much but the workout these little doo-hickies give the chest, shoulders, abs, and arms is amazing. It takes old-fashioned push ups to a whole new level.