Before modern MMA free agency became an item of discussion, Dan Henderson had practiced it years ago. After UFC 100, Henderson's contract with the UFC has been completed, and after a brief period of negotiation with the UFC, chose to walk and eventually sign with Strikeforce.
While Henderson doesn't exactly find himself in an identical position today, it's still relatively unique. Ahead of his rematch with Lyoto Machida at UFC on FOX 19, Henderson is on the last fight of his current deal. The issue for Henderson is how much longer he really has left in fighting. By his own estimation, it's limited and ideally, he'd like to finish out his career in the UFC.