http://playsleuth.com/
This game is my new addiction. It's a murder mystery game where you get to solve cases every day. You can play 4 cases per day for free and more if you subscribe. You play as a detective and you can buy skills with points you gain and get equipment that improves your stats and such. It's really fun.
A couple tips for anyone that plays:
If you still have a person without a motive, it's better to ask the other people motive first and then alibi incase someone clams up because you can't accuse someone or the crime if you haven't found their motive.
You can pretty much be sure someone is guilty if there is:
Physical Evidence + false/no alibi
Witness Evidence + false/no alibi
Witness Evidence + witness evidence
I found that info on the message boards there and it's been true for me so far.