With the rise of HTML5/Css3, a number of web designers in libraries are trying to find the best way to either move their existing sites into a more modern framework, or sometimes just figure out what the big deal is about HTML5. Luckily, there are not only a ton of great resources for reference (like the great w3c Schools info), but my new favorite HTML5 template:
HTML5 Boilerplate
This thing is the swiss army knife of HTML5/CSS3 development. It even supports add-ons, like this really interesting mobile-first extension for Boilerplate,320 and up.
If you’re just looking around for somewhere to start learning HTML5, you could do much worse than looking through Boilerplate and playing with it in your designs.