Kosher bakery or great kosher place to eat out at in Park Slope?
The only thing in the Slope that's kosher is the Chocolate Girl http://www.thechocolategirl.net, and there's not much there. Expensive chocolates, cake, cappuccino from a machine, ice cream, that's about it.
Oh, and the Jewish Music Cafe on most Saturday nights in winter. http://www.jewishmusiccafe.com
Otherwise, take the Q from 7th Ave down to Ave J, Ave M, or KH.