Wikipedia
Hero.com
Hero.com and Villain.net are two series of superhero novels by English author, Andy Briggs.
Hero.com follows the exploits of four friends: Toby, Pete, Emily and Lorna. While surfing the internet during a thunderstorm they discover the mysterious Hero.com site. The nameless icons depict stick-figures in a variety of super-poses. When they click on an icon they discover they can temporarily download superpowers from the internet, into the real world...