Chances are that if you have been a regular visitor to CrackBerry over the years you would have seen us feature TubeMap which is a super application for the London Underground. The app has been available on the PlayBook as well as older BlackBerry smartphones and now BlackBerry 10.
While I was perusing BlackBerry World recently I stumbled upon some more maps from mxDATA which all look to be just as good as the London one and have great functionality.
The ones I checked out Chicago L, Barcelona Metro, Berlin Subway, Toronto Subway, Madrid Metro, Washington Metro, New York Subway and Paris Metro
If you are in any of these cities and have picked up a BlackBerry 10 smartphone I would highly recommend checking them out in BlackBerry World. All are free to download and as well as offering just the maps you can also plan routes - which will tell you the journey time and how many stations you will pass through. It doesn't get much better than that.