Every Saturday starting at 5:45PM the Guggenheim museum allows visitors to pay whatever they like for admission. So if you're broke but still need that contemporary art fix, scrounge whatever you together and head over to the museum. You won't have much time though, the museum closes at 7:45PM on Saturdays, so get there as close to 5:45PM as possible to have the most time to spend browsing the art.
Check out their website here:
Entrance is 'pay what you wish' - Basically, pay as little as NOTHING up to whatever you like. Most people throw in something towards admission, but it really is up to you!
Pay what you wish hours are every Saturday starting at 5:45PM. The Museum stops selling tickets at 7:15PM and closes at 7:45PM on Saturdays, so make sure to get there as close to 5:45PM as possible.
Check out info on the 'pay what you wish' program in their faq: