Do a UK based version. OK, you'd have to play fast and loose with the geography, as some streets are nowhere near each other, but hey, that's artistic license for you.
Do an action / adventure based on chess - we've already had a sneak peek courtesy of the "Many Adventures of a Boy Wizard Genius" who shares his initials with a variety of brown sauce.
Operation - screwball comedy based around a bunch of apparently hopelessly incompetent surgeons. But evidently it would probably turn out that they're so good they could practically do the operations with their eyes closed, and muck about to relieve boredom of performing the 456th quadruple heart bypass of the year...
"Scrambled Letters" - a pair of Indian software developers decide to produce an electronic version of a popular crossword-based board game for use on a popular social networking site, but then get into legal trouble with Hasbro / Mattel because they didn't ask permission beforehand.
Then there's a video game conversion crying out for a movie remake - an adventure/comedy where the protagonist tries to prevent 100 clueless creatures with green hair and oversized blue jumpers from winning a Darwin Award... and somewhat unusually, the backing track will be exceedingly dodgy arrangements of public domain classical / traditional music.
I noticed someone suggested Minesweeper earlier - I dare someone to come up with a credible plot for Freecell - The Movie. Muahahahaha!