Customize Your Home Accessories
An old favorite is WonderfulGraffiti.com, purveyors of eye-poppingly cool wall decals (since way back before wall decals were hot). While the less imaginative (or less geeky) can peruse galleries of stock decals and photos of other people's inspired ideas, the site also offers a whiz-bang cool interface where you can design a room and then try different decals on the walls of your virtual space.
And my new favorite, Design Your Own by Jonathan Adler, offers up something I'd never dreamed of in all my online doodling: customized rugs! The gorgeous, high-quality wool rugs come at a price, but you could be the first kid on your block to have a monogram woven into their carpeting. And even if the high-end pillows (like the one above) and tote bags are also out of your range, it's just as much fun to browser-window shop. Trust me.