Stamen Watercolour Maps — I saw a preview of this a week or two ago and was in awe. It is truly the most beautiful thing I’ve seen a computer do. It’s not just a clever hack, it’s art. Genius. And they’re CC-licensed.
Screens Up Close — gorgeous microscope pictures of screens, showing how great the iPad’s retina display is.
Numbers API — CUTE! Visit it, even if you’re not a math head, it’s fun.