If you're traveling and find yourself without network access, the WiFi Map app can help.
It is a kind of map of public and private Wi-Fi access points, the passwords to which are shared by users around the world. Currently the service gives access to 100 million passwords (the number is growing every day).
To use, download and run the application, and you'll immediately see a map. On it, you should select the place you want and the access point. This requires the Internet, but maps can be downloaded and used offline.