Google I/O

Among other things, the new Firebase (project homepage) is available and supports Android, iOS, and JavaScript. Firebase provides "the tools and infrastructure you need to build better apps and grow successful businesses."

uWebSockets

A lightweight, quick, and adaptable implementation of web sockets in Node.js and C++. 

GitHub

Type

Typographer and web designer Jeremiah Shoaf wonders why, of the over 20,000 typefaces available to web designers, we use fewer than 5%? As it turns out, lists of the 10 top typefaces from the past few years include nearly exactly the same members.

CSS

Keeping along with the theme of type, this article is an excellent introduction to fluid (not responsive) typography. Fluid typography resizes smoothly, rather than switching to an entirely different size at a breakpoint.

Also from Smashing Magazine, an excellent article on the tricky differences and use cases for pseudo classes and elements.

Finally, this article gives a good overview of currently accepted best practices in a changing landscape for coding CSS from scratch, including avoiding bad habits (like only encoding type size as px or %, see above!).

HTML 5

The XSeries of MOOC is taught by W3C experts, so there's no better place to get an authoritative orientation in one of the web's most basic and fundamental building blocks.

The intermediate-level courses start soon and are accepting registrations now.