Head over to Justin Herman Plaza at 10 a.m. on Sunday for a free, three-hour yoga class to benefit four yoga charities, as party of the global Yoga Aid Challenge. But be sure to register first. Can't attend? Donate some money.

So far the San Francisco sector of the event has raised $3,509.07. There are currently thirteen instructors signed up, 56 participants, and the San Francisco charity partners include Off the Mat, Into the World, Y.O.G.A. for Youth, Africa Yoga Project, and 4 Oneworld.