Do your bargain music instrument shopping in the sun. Q Division, the Somerville recording studio that’s hosted the Pixies, Aimee Mann, Mission of Burma and hundreds of others holds its third annual yard sale from 10 a.m. to 2 p.m. Saturday. “Friends and studios who have way too much gear will be joining us to thin out their collections of instruments, audio gear, stomp boxes, belt buckles and much more,” studio head Jon Lupfer says. Everything from cellos and djembes to an Ampeg Reverb Rocket and Mackie 406M-FR Powered Mixer will be available at this family- and pet-friendly free event. People are urged to bring sunscreen (although a rain date is set for Sunday at the same time) and snacks. Q Division is at 363 Highland Ave., near Davis Square, Somerville.

Hit the Cambridge River Festival. With the five-day, electronic-dance-music-focused Together festival and Another’s World’s Fair done, the city’s 34th annual Riverfest celebration of the arts is back with a focus on jazz, folk, roots and world music performances (as well as dance, art demonstrations, family art-making activities and more than 100 specialty food purveyors and artisans). The free event, held along the banks of the Charles River at the Weeks Footbridge at DeWolfe Street in the Riverside neighborhood, attracts some 200,000 people in its half-dozen hours – from noon to 6 p.m. Saturday with a severe weather date the next day. The full downloadable PDF brochure is here.

Laugh your way through a trek “Into Dorkness.” Geek Comedy Night returns to its natural comic book store habitat with a two-hour mission to study and explore geeky and distant realms, ridicule pop-culture icons and mine humorous anecdotes from the beloved artifact known as “Star Trek.” On hand to see if they can faze or stun you are Shawn Superfluous Armistead, Matt Chaves, Leanne Cushing, Rob Logan, Casey Malone, Andrew Mayer, Jake McDowell, John Paul Rivera and Kevin Sawyer. The $5 show is from 8 to 10 p.m. Saturday at Comicazi, 407 Highland Ave., Davis Square, Somerville.

Show off your bike and buy to make it better at a Bike Show and Market. The Massachusetts Institute of Technology hosts this Bike Show and Market – a chance to buy bike stuff from local vendors and individuals as well as a chance to show off what you already have and win (and vote) in such categories as Best Road Bike, Best Mountain Bike, Best Fixie/Single Speed Bike, Best Vintage Bike, People’s Choice and so on. There are also demonstrations planned, as well as sponsored booths with tips, tricks and trinkets. General admission is $1, with children 12 and under getting in free, and bike registration is $5 (starting at 8 a.m.). You can also sell your stuff by setting up a vendor spot for $20 (starting at 7 a.m.). The event itself runs from 9 a.m. to 2 p.m. at the institute’s Albany Garage (also known as Building N4) and N10 Annex Lot, 32 Albany St.

Venture into new musical territory with Nightlands. Easy listening/dream science band Nightlands – the work of Philadelphia multi-instrumentalist Dave Hartley – comes to Central Square to close out the weekend. Nightlands, music literally created in Hartley’s bedroom when he began archiving ideas that occurred in his sleep by speaking them into a simple bedside tape recorder, is made up largely of delicate, chiming strings and bubbling synths beneath a blanket of choral vocal arrangements. “It’s dreamy in the literal sense,” notes the publicists at his label, Secretly Canadian, and “is, in essence, a field recording of Hartley’s dreams.” His music is much like you imagine it would be with such origins: shimmery, delicate and, yes, dreamy, but with more variety than you might think as Hartley steps into brassy areas suggesting bossa nova and Afro-funk. Sample the videos below for a taste of Nightlands’ range:

http://www.youtube.com/watch?v=YsYWxIVwmTs

The show is at 11 p.m. Sunday at T.T. the Bear’s Place, 10 Brookline St., Central Square. Nightlands is appropriately paired with Little Spoon, a project by Cameron Potter of Rochester, N.Y., who opens at 10 p.m. with music he terms blankeywave and pillowpop.