I am from Czech Republic and would like to know if I can buy an internet e.g. for 6 months or a year as a non-Spanish citizen and if yes. If my ID is enough or I need something else too? Also - how much is 1 month unlimited internet via wi-fi in Spain on average?
Internet options in Spain:
- ADSL/Optical Fiber if you have a permanent residence and only want to be connected at home: 30-50 euros/month, 3-50 MBps. The best is Ono, but limited to some big cities. The problem is that most companies have a minimum stay time of 1 year (if you go early you will have to pay a "fine").
- Mobile solution (USB or Mobile Phone): from 9 euros/month for 1 Gb at high speed (HSDPA) then "normal" (very slow) speed. The cheapest option is Yoigo. You can buy an USB stick or a spanish SIM card with your passport and pay only for the months you'll stay. Another option is a dongle that you will pay only if you use it (about 1 euro per day).
- Free wifi: there is a big number of "open" wifi points arround spain, also it could be interesting the Fon project pointed by @mouiciel. Anyway, it will depend on which city you stay, in Barcelona or Madrid is relatively easy to find an open wifi spot. Other options are some restaurants (like McDonnals), public libraries and some malls.
To buy any internet connection, you'll have to know some spanish or it will be difficult to understand with the seller (better in big and touristic cities)