This is the best breakdown of selectors I've seen. An excellent reference for all Web developers.
"Inspired by American portrait painter Chuck Close, this script converts an image into a pixelated version using an HTML5 canvas element. It's basically a simple demo for canvas' imageData functionality."
As noted on the site, this is "the professional badass's base HTML/CSS/JS template for a fast, robust and future-proof site" While I likely won't use this whole, there are some very interesting pieces to this worth using, especially in the style sheet and .htaccess files. I'll likely appropriate many of the concepts for my work.
This is an outstanding contribution to the Web development community by Paul Irish and Divya Manian as well as all of the people whose work they built upon.
This site provides "an indication of how well your browser supports the upcoming HTML5 standard and related specifications."
If you want to use HTML 5, the shiv is pretty well a requirement as Internet Explorer (up to and including IE 8) doesn't support the new elements in the spec. Plus it's easy to implement and will only be downloaded by the browsers that need it.
Cheat Sheets & Quick Reference Cards for Developers