Over at Lifehacker, they have a step by step guide to How to Hang Pictures Without Destroying Your Walls. One of the tips we liked was this one:
Bonus Tip: Use Disposable Hooks
3M’s Command line of plastic and metal hooks also work well to hang light pieces of art and posters from drywall or concrete, without the need for drills or nails. Apartment dwellers in rental units, college students, or anyone else who’s technically prohibited from hammering or drilling will find them especially useful. The adhesive strips that come with Command hooks go on easily, cure quickly, and remove without damaging the walls (in most cases,) which is a huge benefit if you like to change out the art on your walls frequently, or just don’t want to risk drilling or hammering nails into them.
The trouble with these kinds of disposable hooks, Velcro strips, and other mounting strips is that they’re generally rated for very light objects. If you have small, light plastic or acrylic frames with photos or printed posters in them, they’ll work well. If you have a solid wood frame or oversized pieces of art, they may hold for a few days, but your art will come clattering down unless you use three or four hooks to hold it up.
Check out the very informative full post.