Duke Nukem Forever
This is actually the winner of a DNF fake screenshot contest, so all the hard guessing work is done for us. The Gila Monster logo, though, is so right for the game we wouldn't be surprised if this was a real screen, in some backwards reverse anti-marketing skit by DNF devs 3D Realms.
PS3 in-game XMB
The things people fake is always amusing. Who fakes an in-game XMB? That said, the fuzzy focus and indistinct image behind the XMB do add to a decent - if never convincing - attempt. Still, why not fake something interesting?
Super Mario Galaxy DS
Sorry. That thing about the in-game XMB was awesomely dull. So why not enjoy this fantastic fake footage of the DS-compatible unlock apparently hidden away inside Wii's Super Mario Galaxy to take away the dreary mind-taste.
Half-Life 2... Again
Another trick for fooling people with your fake image is putting "HL3 Demo" followed by meaningless letters in the corner of the screen. It doesn't work if you've just pasted the HUD over a photograph, though. Doh.