Apparently, Monday through Thursdays through 4/21, you can get $10 in free play when you visit the Players Club and produce a Greektown card. I would assume that this is also true for the Motor City card, but who knows.
This is not at the website but I saw numerous people doing this today.
Also, tomorrow is the last day to pick up a $50 Honeybaked Ham gift certificate for earning 2500 points between March 29-April 9.