Things to do this weekend for (mostly) free
Korean festival and parade Dance, taekwondo, food, music and cooking lessons.
Chile Pepper Fiesta, Brooklyn Botanic Gardens Music, chile-chocolate cooking, Qigong lessons, and hot stuff samples. Free with admission to the Gardens ($8 adults, $4 students, seniors, and kids over 12. Kids under 12 free)
Colonial Day, Fort Greene Park Hands-on games, cooking and butter churning
Garden walking tours overlooking the Hudson in Fort Tryon Park
Family Day at the Whitney A day of Georgia O'Keefe for $10/family
Czech Street Festival Music, raffles, and serious street food
Archery lessons Equipment provided
Autumn Moon Harvest Festival, Chinese Scholar's Garden, Snug Harbor Cultural Center, Staten Island
Leukemia & Lymphoma Society: Light the Night Walk, Staten Island
Medieval Festival, Fort Tryon Park (pdf) Performers, craft vendors, medievalish food, live chess, jousting, the Society for Creative Anachronisms, and every year's greatest roaming costume parade on the grounds of our local medieval monastery. Like a Ren Faire, only earlier.
Atlantic Antic street fair 10 blocks of street food on Atlantic Avenue in Brooklyn
EcoFest, Central Park
Bronx Museum Open House and Street Fair Music, dancing, local food vendors, activities for kids and free admission to the museum.
They Might Be Giants, under the blue whale at the Museum of Natural History - free with museum admission
Apple Festival and pick your own pumpkin at the Queens County Farm Museum
Rockaway Fall Festival Pumpkins, ponies and hay rides at the beach
Catapult Month events at the NY Hall of Science, Queens: explanations and thing-hurling.