Like many people, "art"—meaning what you find on the walls of a gallery—isn't really in my budget. It's sad, but that's how the market fot it is. I've just never made enough money, or had the type of eye that I trust to know what it's like to live with a work. (I did, however, have a Chagall sketch on my wall for a few months, but that's another story.)
So I buy beautiful posters. Or did, while I still was salaried. There's so much great graphic design now, most notably in the indie rock world, that it's inexpensive enough to buy a bunch of cool pieces.
Many companies put out great, and limited, posters-as-art as well. I particularly like Scorsone/Drueding, whose poster "Alternatives to War" you see above.
Ethnic Cleanser is especially good, and a little uncomfortable.