Brooklyn Based has a great list of recession busters. Here are some examples in the Park Slope area:

—The Dweck Center for free music, readings, and cultural events.

–the monthly First Saturday parties at the Brooklyn Museum. Those are awesome free dance parties.

–Bierkraft’s Tasty Tuesdays:
Speaking from experience, these free cheese and beer tastings are
great. Enthusiastic guest speakers, you learn something about what
you’re eating/drinking and it’s totally free.

These two about sushi and donuts came from Fucked in Park Slope:

–Bonus: Yuppie Scumbag Luxuries that FIPS can’t give up (their own Recession-inspired list you must check out too):

Sushi. But you can go to places like Park Slope Seafood and get prepackaged, yummy (but way cheaper) sushi. If you are really Ballin’ it, I recommend the volcano roll at Jpan…it’s
in a friggin’ PANCAKE. Also, it’s not on the menu, so it’s kinda like
one of those super cool bars that doesn’t have a door.

FIPS also mentioned Donuts as a recession-proof eatery.