Apparently if you live in Germany you can get fined for not password-protecting your Wi-Fi network. This is because courts ruled that you're responsible for anyone who takes advantage of your Internet connection to pirate files or cause other troubles:
Germany's top criminal court ruled Wednesday that Internet users need to secure their private wireless connections by password to prevent unauthorized people from using their Web access to illegally download data.
Internet users can be fined up to euro100 ($126) if a third party takes advantage of their unprotected WLAN connection to illegally download music or other files, the Karlsruhe-based court said in its verdict.
"Private users are obligated to check whether their wireless connection is adequately secured to the danger of unauthorized third parties abusing it to commit copyright violation," the court said.