I found ARTMARCOVICI from the oddly-name But Does It Float, which I found from the Some Random Dude mailing list and blog. There is, of course, regular interesting art there. But he also has some interesting concept pieces I found fascinating. Some are futuristic designs, some are more sociopsychological in nature. I love the high-tech futuristic stuff, but what kept me on the site is the creativity and diversity.