Have you seen Green Goose? They're doing some beautiful stuff with sensors for consumers: turning everyday activities into games. I love the mundanity of it all: keeping the toilet seat up, brushing your teeth, walking the dog. One of their apps is called "BrushMonkey". It doesn't get any better than this.
They've been around for a little while - there's a story on RWW about them from early 2010, but they seem to have changed tack since then, away from financial monitoring and towards fun'n'games. Here's an interview with their founder from December last year. Green Goose seem to be spreading themselves thinly across many applications: "We’ve got about 50 or so other sensors in development right now that we will fairly quickly release over time".
Their hardware seems similar to Little Printer, in that they have their own gateway (the "station egg") which plugs into the spare port of a hub.