You’re practically a Houdini when it comes to making tears disappear. But conjuring a babysitter out of thin air is another story.

Let UrbanSitter round out your bag of magic parenting tricks.

A social app for finding, interviewing, and scheduling babysitters, including the hard-to-find, last-minute kind, the service uses Facebook Connect and your affiliations (think Music Together or SoccerTots) to layer your friends’ reviews over a list of available caretakers. The 300 sitters — most of them USF and SFSU students or grads in child development and nursing — post their credentials, hourly rates, and location preferences online.

Either book right away (your confidence inspired by what your friends have said) or request an interview. Not in the city? The service extends to the Peninsula this week and East Bay in early October.

Now, if only you could pull a 7:30 p.m. reservation at A16 out of your hat.

Available online at urbansitter.com, free.

CREATE
Make Art Workshop: Seed Mosaics
What: Museum of Craft and Design pros teach aspiring artisans (6 and up) to collage with natural materials.
Why: Grow their talents.
When: Sat., 2-3:30 p.m.
Where: Main Library, Children’s Center, 100 Larkin St., b/t Grove & Fulton Sts. (415-557-4554). Free.

AUTUMN
Mill Valley Fall Arts Festival
What: A woodsy weekend celebration with marionettes, music, and hands-on crafting.
Why: Fall under the spell.
When: Sat., 10 a.m.-6 p.m.; Sun., 10 a.m.-5 p.m.
Where: Old Mill Park, 320 Throckmorton Ave., nr. Old Mill St., Mill Valley. Info at 415-381-8090. Adults, $5-$10; children 12 and up, $5; children 11 and under, free.

CROON
The Little Mermaid Sing-Along
What: Atlantica drag, audience participation, and the beloved 1989 flick with subtitles.
Why: Your girl will kiss you.
When: Fri., 7 p.m.; Sat. & Sun., 2:30 & 7 p.m.
Where: Castro Theatre, 429 Castro St., at Market St. (415-621-6120). Tickets online at ticketweb.com. Adults and teens, $15; children 12 and under, $10.

Photo: Thinkstock