Two-thirds of small businesses use social media to promote their websites, according to a survey from site for freelancers, PeoplePerHour.com.
Facebook is seen as the most effective platform (55%), followed by LinkedIn (20%) and Twitter (19%).
Xenios Thrasyvoulou, CEO of PeoplePerHour.com, said use of social media is becoming more common among SMEs.
"It's easy to see why it has proved so popular for small business marketers in a recession: they're free to use and have virtually limitless reach," he said.
Location-based networking service Foursquare is also growing in popularity, with 9% of SMEs now using it.
However, of the 1,300 SMEs surveyed, 74% said they have not heard of, or do not see a business need for, cloud computing.