Excellent simple concept! Until it lost all my saved wifi spots mysteriously. A backup would be handy in cases like this. Anyway, much better than any GPS based idea. Go download it already! Edit Update 13/01/14: continues to regularly delete my saved wifi hotspots and more importantly my notes, so it's too unreliable right now for dependable use. A shame, but hopefully it's a small bug that can be fixed. 2 stars until resolved.
Fixed possible loss of data.