A small colorful action-packed exhibit, the Cartoon Art Museum consistently surpasses expectations. Check the website for exhibits and events (including cartooning classes!)
An easy detour from the Yerba Buena Gardens circuit (MOMA, Zeum, etc) in the SOMA/Downtown area.
Address: 655 Mission St, SF, CA
Wikipedia: http://en.wikipedia.org/wiki/Cartoon_Art_Museum