Brooklyn Botanic Garden's free hours: Saturdays 10:00am - Noon.
Greenwood Cemetery: Drive or walk in (be prepared for a strenuous hilly walk). Get a map and look for notable New Yorkers final resting places. Sit by one of the 'lakes' surrounded by gorgeous mausoleums eating pre-packed Peanut Butter and Jelly Sandwiches. Admission: free. Sandwiches: Cost of Jiffy, Smuckers and Wonder Bread.
Cobble Hill Cinemas: $6.50 nights at Cobble Hill Cinema, Tues & Thurs.
Transit Museum: $5 admission all the time.
Lefferts House: Free. Lots of activities for kids.
Brooklyn Museum: Suggested admission $8 (suggested means, pay what you want. If a buck is all you have, you will not be denied).
Fairway: Walk in and have a tea or coffee and sit by the water.