I went to Kent State in the late 80's/early 90's, and we had no recycling available on campus. The students of McGilvrey Hall took matters into their own hands. I'm not sure who was responsible for it (the Geology department was the main suspect) but they had a very clever approach.
A number of recycling bins, clearly labeled, were placed next to the trash cans in the main hallway. A black-and-white bumper sticker reading "THINK" was placed on the lid of the trash can.
You know what? I did think, every time I used that trash can. I never threw away a recyclable.
I've thought about having some stickers printed up, but as I was looking around on-line, I discovered that cafe press already has them. (They come in a rectangular form as well.)
We should really take the time to think before we commit an item to the trash bin. Is it recyclable? Compostable? Could somebody else use it? Some things are rather unequivocally trash, but is everything?