Sure, this weekend is the Head of the Charles Regatta, the 47-year-old, two-day rowing competition, and if that’s what you want, it’s not hard to find: More than 9,000 athletes and 300,000 spectators are expected, so follow the crowd to the river.

But there is always other stuff going on, and here’s some Cambridge and Somerville counter-programming you can engage in:

The legendary monthly Swapfest flea market returns Saturday to the Massachusetts Institute of Technology. (Photo: François Proulx)

Stick close to MIT for Swapfest, a book sale and free showings of “The Rocky Horror Picture Show.” Swapfest is the legendary monthly high-tech, computer, electronics and ham radio flea market where you can “buy, sell or swap all things nerdly” between 9 a.m. and 2 p.m. in, appropriately enough, a garage, namely in the Albany Street Garage and its adjacent lot. The event costs $5 (or $4 with a Massachusetts Institute of Technology ID card) at Albany Street between Massachusetts Avenue and Main Street, near Central Square. For information, call (617) 253-3776 or send e-mail to [email protected].

The MIT Press Bookstore Loading Dock Sale takes place 10 a.m. to 6 p.m. Saturday and Sunday   at 292 Main St., Kendall Square, with the institute’s calendar labeling both days open to the general public; the bookstore’s own site says only Sunday is open to all and that Saturday is limited to those with college ID. The store says “literally tons” of books will be on sale at up to 90 percent off original retail prices, including overstock from the MIT Press and other publishers, out-of-print MIT Press books, books with minor damage and back issues of academic journals. These books are not for resale, so there’s a 40-book-per-buyer limit(!) and no digital scanning devices allowed. For information, call (617) 253-5249 or send e-mail to [email protected].

Finally, for those missing the cult film “The Rocky Horror Picture Show” after the end of its 28-year run in Harvard Square — it moved to Loews Boston Common in Boston in August after the AMC Harvard Square cinemas shut down in July — it shows at 7 and 10 p.m. Saturday at the institute’s Building 26, also known as the Compton Laboratories, off Vassar Street between Massachusetts Avenue and Main Street. The building is behind Building 36, also known as the Fairchild Building, 50 Vassar St. It’s not the classic midnight showing … but it is free and local.

Get hungry and have a hero at Cambridge Food Day Week. That was not a typo. Wednesday is Food Day, the second annual nationwide celebration of healthy, affordable and sustainably produced food, an event intended to have the grassroots feel of early Earth Days and orchestrated by the nonprofit Center for Science in the Public Interest. But Cambridge has a whole week of Food Day-related activities, which makes this Food Day Week. (And need it be said? It makes this month Food Day Week Month.)

Saturday brings four chef talks on a variety of topics (including Didi Emmons of Veggie Planet, The Blue Room and Boston’s Hamersley’s Bistro on “Chefing for The Greater Good: How One Chef has Forged a Path in Public Health”) from 2 to 5:30 p.m., followed by a 6 to 8 p.m. Farm to Table Reception & Food Heroes Awards event with hors d’oeuvres, food demos and local beer and wines for $5. Five food heroes will be honored, including Steve Johnson, chef-owner of Rendezvous in Central Square, one of the founders of the Chefs Collaborative and the first chef in Cambridge with a rooftop kitchen garden, and Jane Hirschi, founding director of the CitySprouts public school garden program. All of this happens at Le Cordon Bleu College of Culinary Arts in the Athenaeum Building, 215 First St., near the Lechmere green line T stop in East Cambridge.

Sunday brings a 5 to 7 p.m. potluck at the Cambridge Community Center, 5 Callender St., for which people are asked to bring food and reusable stuff to drink and eat on, from and with. Organizers plan to share information about the upcoming Cambridge Winter Farmers Market during the potluck.

A cook readies more meat at last year’s Rib Fest in East Cambridge. (Photo: Tim Toomey’s Community Blog)

Gorge yourself at the “Smoke This” Rib Fest. If potluck isn’t your style, on Sunday the East Cambridge Business Association’s annual culinary showdown looks to pin down who has the best ribs in town. But who cares about a winner (except, probably, the competitors) when no matter who takes the gold you get to eat barbecue and other foods from restaurants including Abigail’s, Area Four, Artbar, Atwood’s Tavern, Bambara, Catalyst, the Cambridge Rindge & Latin School Culinary School, East Side Bar and Grille, Lord Hobo, Midwest Grill, New Deal Fish Market, Ole Mexican Grill, Portugalia, Lizzy’s, Trina’s Starlight Lounge, Tupelo and West Bridge? Other events are planned as well, including cooking demonstrations from local chefs, kids’ games and bands playing bluegrass and Americana.

A Taste Ticket gets you 10 rib samples from the restaurants of your choice, but it’s first-come, first-served. Tickets are $20 (with a $2.09 fee) here. For information, send e-mail to [email protected]. The event runs noon to 4 p.m. Sunday on Cambridge Street between Fulkerson and Fifth Street in East Cambridge.

The winners of the 2011 Halloweeniversary event hosted by the comic store Comicazi: a two-person At-At from “The Empire Strikes Back.”

Party at Comicazi’s free 12th annual Halloweeniversary. The Davis Square comic book store Comicazi brings music, food, a costume contest, cash bar and comics-lover raffle to the George Dilboy VFW post, 371 Summer St., Davis Square, Somerville, for four hours starting at 8 p.m. Saturday. In the past, the raffle’s grand prize was some comic book worth hundreds of dollars (last year it was Uncanny X-Men No. 94, the reboot that introduced characters such as Wolverine to the team); this time it’s a graphic novel of the winner’s choice — worth $19.95 or less — every week for a year! Here’s how the store’s PR puts it: “Sweet Christmas! That’s right, folks, 52 graphic novels are in the offing for you to win.”

Take the kids to see the Rolie Polie Guacamole family show. Club Passim is hosting this costume party with Rolie Polie Guacamole, one of the hippest of the “kindie” band from Brooklyn and therefore intended to be tolerable if not enjoyed by adults, at 10:30 a.m. Saturday. The band is in town to celebrate the release of its third album, “Houses of the Moly,” a cover album of traditional children’s songs, featuring fan favorites: “Dragon Hunt,” “Upside Down” and “Fire Truck!” — not the roughly three-second song written by a 4-year-old and popularized by Mike Doughty of Soul Coughing. Tickets are $10 at Club Passim, 47 Palmer St., Harvard Square.