johnnyhollow.com - click "Enter Our World Here"
This site is beautiful. Seriously. That's the only word fitting for it. It's really surreal and the artwork is freaking amazing. I can honestly say it's the best digital art I've ever seen. It's basically a website made by a Mr. Vincent to show off his (magnificent) artwork and his (awesome) music. By clicking on the butterflies you're taken to a page where you're given a riddle. If you solve the riddle then you get a free song to download and some desktop wallpaper. Most definitely it is worth it. Make sure you have the sound on when you view the site - it doesn't play music, but there are sound effects like murmuring voices and fluttering wings that really add to the experience.
http://www.mypetskeleton.com/ - another site made by the same people. Just as awesome. It's even more surreal than the first site and with much more beautiful artwork. This one also plays music. =P