Protect your Wi-Fi network in Germany, or pay the piper (in German): The piper, in this case, being music industry or other rightsholders. Germany's Bundesgerichsthof, the highest appeals court for civil and criminal matters, ruled in a case stretching back to 2006 about a song downloaded from an open Wi-Fi access point by a third party--not the owner of the access point, who had left the location unprotected.
The court said that actual and punitive damages weren't warranted in such a case, but that a kind of statutorily defined penalty of €100 did apply. (The term is Abmahnung, which seems to be a sort of compulsory penalty that doesn't require a court case to be levied.)
Update: A commenter who knows more than I do (that's why we like comments) explains that the fee is a "civil pre-trial settlement to avoid a costly civil trial if the facts are clear."
The court said, "Private individuals can be held responsible for default judgment, but not for claims of damages, when an unauthorized third party makes use of an insufficiently protected wireless LAN access point for copyright infringement."
The decision is welcome in Germany, because it removes a lot of worry about unlimited fees (such as have been levied only directly against filesharers in the US), and the fees that can be collected are small enough that the various copyright holders may not pursue them.
Nonetheless, the precedent now allows these fees to be collected, and that does change the equation.
Germans thus warned ought to enable any kind of encryption. The linked article notes that even WEP, though it's easily broken, would qualify because then the third party would have to break into the network (a fairly severe crime in Germany since 2007), making the access point's owner not liable.