CSS3 Image Styles is a terrific tutorial explaining how to use CSS3 and background images to do some very cool things.
You can now read HTML5 for Web Designers by Jeremy Keith online. This is an excellent book, go read it. The site is built in HTML5. Look under the covers.
I’d like to examine this infographic of the history of web standards. I can’t zoom it large enough to read. That’s my problem with most infographics. Got any good ideas about how to make it readable?