Myxer has surpassed 10 million users, 20 million downloads per month and almost 150 million mobile downloads in total since launch, the company said today.

That makes Myxer the largest free, ad-supported mobile community on the Internet and one of the top 500 Websites in the United States (Alexa), according to the company.

Myxer previously announced reaching the 1 million user mark in April 2007 and is now growing virally at an average rate of more than 40,000 new users per day.

Myxer, which is both an online and mobile community as well as a mobile content delivery platform, also announced that McDonald’s, the U.S. Army, NBC, Friendly’s, ABC Family and other major brands are now using its mobile platform to deliver branded mobile content and integrated digital ad campaigns to targeted audiences, spanning the Web to mobile environments.

Myxer’s 10 million users are made up primarily of teenagers and college students.