Magazines

Start a pile of magazines. Your own, ones friends gave to you, ones that places throw away (libraries, book sales, and rummage sales tend to have very inexpensive ones they want to get rid of, also check Half Price Books). Go through, and clip out all the images you love. Put them in a large sketchbook, or on 8.5 x 11 sheets of paper. If the latter, you can organize them into binders by topic. Look through them when you're feeling restless.