For what it's worth, this blogger's personal limit appears to be three. Currently, the list includes World of Goo, The Legend of Zelda: Ocarina of Time (after a decade away), and Fallout 3 (my dirty secret: I also own a Xbox 360). Meanwhile, an imported copy of Chrono Trigger DS is being neglected, simply because I couldn't cope with another game where I need to keep close tabs on the story. Yes, I am ashamed.
What's your maximum playload?