In Dead Rising 2: Off The Record for the PC, PS3, and Xbox 360, you can collect the Gambling Magazines to greatly increase your odds at winning on the slot machines.
Note that you must keep them in your inventory for the effect to last.
Gambling Magazine 1 – In Palisades Mall, on a table above the pool bar near the slide
Gambling Magazine 2 – On the top floor of Bennie Jack’s BBQ Shack in the Americana Casino, sitting on a ledge on the left
Gambling Magazine 3 – In Uranus Zone Bank, Security Box #304, the key to the box is sitting on the unfinished wooden ledge in Fortune Park to the right of the Fortune City Hotel entrance