Part of the fun of LEGOs is improvising with them. But for those who prefer more structured play, a new, free app called Brickit may be the ticket. You use your phone to snap a photo of whatever LEGOs you have on hand, and the app tallies up their sizes and shapes. It then provides different options for what you can build with the pieces you've got, even if you're a few bricks shy.
As far as we can tell the app is not officially LEGO-affiliated, but hopefully the toymaker won't put the kibosh on it.