The Ultimate Accessible HTML and CSS Checklist for Developers: part 1 is from access iQ. It may not be the ultimate list, but it is a new way of presenting the items in WCAG 2.0 in a reader friendly way.
At SitePoint, there’s an article about CSS Architectures: CSS Best Practices that has good code examples.
The hgroup element in HTML5 is kaput.
Thank you for the positive feedback on our checklist. We will be publishing the second and third parts over the coming weeks, and we hope that all three parts combined act as a beneficial resource for developers.
Thanks. Would love it if you’d let me know when they go up.