Things to do as a couple (or with close friends) without spending money?

Lets hear some creative ideas. I am always at a loss for them. Once in a while we go out and do fun things, but it always seems like we end up spending money. Keep in mind all times of the day/night and creativity is key!
Ideas already used that I can think of are going out and flying kites. (Failing miserably at that, too.) Picnics. Art Museum. More walks than you can imagine.