U.S. companies are expected to spend an estimated $1.8 billion at MySpace.com and competing social networking sites by 2010, up from $280 million this year, research firm eMarketer said Tuesday. Companies with businesses built on creating buzz need to tap into social networking destinations such as MySpace to effectively market their wares. Still, social network ad spending will account for only 1.7 percent of the $16.7 billion spent on U.S. online advertising in 2006, rising to 6.3 percent in 2010.Warner Independent Pictures launched in April a site on MySpace.com to promote the movie “A Scanner Darkly” in an effort to connect with moviegoers. When Sony Pictures Entertainment recently released the movie “Monster House,” the studio posted character profiles on MySpace.com to attract consumers of all ages to a movie they otherwise might not have seen. Character pages appear to tend to work best, especially on MySpace.com, where users can become “friends” with character. For example, Sony created a profile page in the voice of Jill before launching the movie “When a Stranger Calls.” “Jill had 89,000 friends when we opened the movie, and nearly 110,000 friends by the time the movie went into the home entertainment window.