The last idea that sounded really original was on an episode of the TV show Crazy Like A Fox. Guy was framed for murder, convicted, sentenced to 20 years. Served his time, got out, and decided to really kill the guy who framed him - and who he was already convicted of killing. Since he'd already served his full sentence for killing the guy, he figured he couldn't be tried again (Double Jeopardy) and the state owed him a freebie. (They made a movie about 10 years ago based on this premise.)