SFist already let you know about the big Rapture Party, ArtPadSF, and Sex Worker Fest going on this weekend. Here's even more stuff that's happening.
BlacKMahal + Guests: Bring a picnic to the lovely Yerba Buena Gardens on Saturday for BlacKMahal, a San Francisco-based live music experience that's "part P-funk, part Punjabi-roots," complete with drums, DJs, horns, hip-hop MCs, and the godfather of Punjabi-American music - Ustad Lal Singh Bhatti, representing "the new California feel: hippy hybrid hip-hop and hysterical hi-jinks."
Pickin' Party 2011: Or, if rootsy Americana is more your thing, head to Golden Gate Park on Saturday for the California Bluegrass Association's annual pickin' party. Bring your own instruments, friends, family, and some food to put on the grill, and get ready to jam.
Maker Faire 2011: Check out the Life-Size Mousetrap and many other fun and surprising curiosities, and attend various art, crafts, engineering, food/sustainability, green, music, and science workshops at Maker Faire 2011 at the San Mateo Event Center all weekend.
Circus Carnival's Spring Carnival: If you don't feel like leaving the city for your circus/steam punk vibe on Saturday, you can always head to the Circus Center for their annual Spring Carnival instead. Carnival-goers are invited to try the flying trapeze, learn to walk the tightrope or on stilts, or juggle. There will also be face-painting, concessions, and all kinds of circus activities throughout the day.
SF Underground Market: It's another Underground Market extravaganza on Saturday at Public Works put on by ForageSF. Taste and purchase take-homables, hot food, and gifts during the day, and come back for hot food and music later that evening.