Subway map design can be brilliant information/graphic design at it's best.  London tube map is based on Harry Beck's original design. His design has also set the standard for other big city subway maps.

The revolution was that the Beck's map bears no similarities with real life. He was sure that people didn't care about the geographical accuracy rather than topology of the railway. People just want to know where to change and how to get from station A to station B. Dave Trott refers Beck's design to wiring diagram instead of a map.

Compared to London tube Helsinki Metro system is pretty simple (read: boring). However, it is been said that big city subways equals big city problems. This means that the only problem we are left with in Finland is the redesign of the Helsinki metro map. 

BTW, check all the metro logos in the world here.