Check out the sexy line work from ZSO (aka Sara Blake), an NYU graduate and freelance illustrator from New York. At first glance, I though most of her pieces were drawings or watercolor paintings but some of them are also digital pieces. Her site has a few videos showing the evolution.
I also love her blog in which she showcases her work from various angles. I like when artists try to give the full effect of their artwork because things can seem intangible and a little flat on the Internet.