FREE Drive-Thru Movie... Without the Car

Bryant Park

http://www.bryantpark.org/calendar/film-festival.php
Hudson River Park

http://www.hudsonriverpark.org/events.asp?date=7/2009&day=1&size=large
RiversidePark
http://nycgovparks.org/sub_things_to_do/events/output_pages/images/summer_on_the_hudson.pdf
Brooklyn Bridge Park

http://www.brooklynbridgepark.org/index.cfm?objectid=EF670B44-3048-2C77-F20C2202337458ED
Sony Wonder Tech Lab (k, so this one's indoors, but it's FREE)

http://wondertechlab.sony.com/pe-feature_screenings.html
River to River (all over the city...)

http://www.rivertorivernyc.com/events/index.php
McCarren Park Pool

http://www.mccarrenpark.com/film.html