I actually worked here as a guide before I moved to Stockholm. There are heaps of German and Japanese tourists visiting, but to be honest, I don't really see why! (luckily I am not emplyed anymore, so I don't risk getting sacked :)
We'll the entrance fee is not much (sek 30), so if you have a spare day you might as well visit, but it's not worth making a special visit to Grängesberg just to see it!
Basically, it is a collection of 135 old locomotives, and one of them is the world's only working locomotive.
Dan Anderssons finnstigar is hiking paths around Grängesberg. You will see the old cole mines which are special for this area of Sweden.
Spendrus, one of Sweden's largest breweries are in Grängesberg. They have guided tours, so if you like to see how beer is brewed, go there! A few years a go you got free beer after doing the tour, but now I think you'll only get lemonade! :)
You can also tell by the smell over the village that there is a brewery here!