http://www.demap.info/tetsudonow/ (http://www.demap.info/tetsudonow/)
Note that while it's advertised as "real time", it's just showing trains according to their schedule, not the actual location of the trains right now. But since this is Japan, it's mostly accurate enough.
No OpenStreetMap background :(
Anyway, nice, especially the "accurate enough" :D
oh cool, looks like they have one for Switzerland too (sorry, again Google Maps): http://simcity.vasile.ch/sbb/
Both simulations... for Czech railways it would read "model includes standard delay" :P
Real data based English one:
http://traintimes.org.uk/map/#bhm
Wasn't there a thread with these, about a year ago?
Interesting this should come up today: http://www.opentraintimes.com/maps has just released some new live signal block maps based on Network Rail's open data program.