The Adventure Seed
A friend of the Party, (or perhaps a party member) is an editor for a Wiki-based database, and has been having trouble with an annoying troll. Someone keeps adding nonsensical entries and making bogus factual statements; such as saying that the Protestant Reformation was started by John Hus, or that the Ottoman Turks were driven out of Europe by Bohemia, or that Austria was annexed by the Czechs. The weird thing is that the cybervandal seems to have an untraceable ISP address.
The PC's resident computer expert is asked to investigate and discovers that the changes to the Wiki site are actually originating in an Alternate Universe in which Bohemia became a major power in Central Europe and Prague is one of the major capitals of the world. It's also a Universe where magic is common, and some magical congruence between the Wiki's web server and one in the other Universe has led to a connection between the two.
So, having discovered this connection, what will the Players do with it? Can they gain information on magic that they can use? Will other, more nerfarious forces seek to exploit the connection for their own benefit? Can they figure out how to use the connection to visit the other Universe? Will Hussite Sorcerers from the Alternate Universe come over here?