Spanish is the third most used language on the web according to an article from El diario Montanes from Spain

Spanish recorded a growth of 600% in just eight years  on the Internet according to the Spanish newspaper.  The use of Spanish on the Internet has taken a giant step forward. There are almost 131 million Spanish speakers users and is the third language used in cyberspace. Between 2000 and 2008, the use of Spanish has grown by 619%, which contrasts with the 227% increase use of English.