Murdered: Soul Suspect is one game I'm paying some serious attention to as it's just so damn original. You're a ghost who has to use ghost powers to solve his own murder.
I got to see a pretty extensive demonstration of Murdered a few months back and now you can see exactly what I saw. The walkthrough starts near the very beginning of the game, and shows off how you'll use ghost powers and your own detective skills to figure out who or what killed you.
Also, ghost cigarettes.