A fantastic post / trip down memory lane on the insanity that was developing for the web (the post touches on HTML and JS, not just the CSS of the title) from the late 90s through today.
Notes about css
A decent roundup of ways that you can fine-tune your word/character-level typography on the web — I don’t 100% agree with all of his suggested specific fixes, but knowing how one can make these adjustments in the first place is the important part. I might also add mention of the CSS overflow-wrap: break-word rule which has come up twice as something I needed in the last couple of projects I worked on (okay, that’s not really a spacing technique so much as a fix for overly-long words, but thought it worth mentioning alongside font tweaks)
Oh my, yes. The Firefox team has an experimental specification for making use of the advanced features of OpenType and AAT, possibly through the CSS @font-variant property. This could get hairy rather quickly and I have to imagine it’d be tricky to write out the full description by hand, but the typographical goodness would be hard to pass up. Be sure to check out the hack.mozilla.org page about this to see some nice preview images.