If anyone is into trains (and/or subways), there's a really neat/fun/bizarre South Korean subway simulator app called Hmmsim (it's free, on the iPhone App Store - not sure if it's available for Android as well).
That's more like a train conductor sim (along the lines of Densha de Go! on PSP). I just ran across a puzzle game along the lines of the submission on gog the other day: http://www.gog.com/news/release_mini_metro
There's a similar simulator for the UK's "IECC" signalling systems (Integrated Electronic Control Centre), including a fairly large number of maps and a reasonable community for chaining maps for multiple signal areas together. It's incredibly addictive http://www.simsig.co.uk/
If anyone is into trains (and/or subways), there's a really neat/fun/bizarre South Korean subway simulator app called Hmmsim (it's free, on the iPhone App Store - not sure if it's available for Android as well).