Pretty interesting post over US News' "Fresh "Greens" blog regarding what to put in your recycle bin and what not to.
Pizza boxes are bad. Seriously.
Pizza boxes. The oil from pizza can contaminate cardboard boxes, making it impossible to process them into clean paper.[VIA: Fresh Greens]
Napkins and paper towels. It's not the paper goods themselves that present a problem, but the fact that they're typically used to wipe up food, cleaning products, and other "hazardous waste."
Sticky notes. Their size, color, and the adhesive strip make them a better bet for the trash bin.
Plastic caps. Curbside programs won't recycle them, but Aveda collects them and turns them into packaging for new products.
Wet paper. Paper fibers that have been exposed to water are shorter and therefore less valuable to paper mills, making it unprofitable to collect and recycle.