I could use it to sort the kids' Lego-covered bedroom! Make a handheld version that accepts a certain colour at a time and spits anything else back to the pile to simplify from a range of bins to more of a yes/no operation.

Interesting idea, that's worth thinking about. It still has the bad part of the complexity: the feed mechanism. But it could be used as a set extractor that way, and if you start with the largest sets you get the least # of bricks passing through.