The best idea I can come up with is put some of your artwork on popular art sites like deviant art. You would want to put a watermark on the ones that you post of course and in the description have a link to where they can buy it on your site. (As opposed to selling it though the site which I would think would make you less.)
Also, once people start to take notice of your art, make a Facebook fan page for it. You can post a couple watermarked pieces there as well.
Watermark it first so others can't steal you work. The next thing you can do is find websites of your choice, preferably Art websites. But there are a lot of photosharing websites that you can upload to. Also you can use facebook and make a page there and upload new content everytime to keep people interested. Then make a twitter account linked from your facebook account and get people to join there too.
Maybe you can try video marketing too. You can use PhotoStory or other software to make video with your art pictures and music. Then submit them to video sites. You can add your contact information or site link on each screen.
YouTube is a good site. If you like to try more, here is a video site list