XHTML Resources

HTML Entity Table
An "entity" is a character that's given a name or a number. For example, "<" is the name for the "less than" sign, "—" is the UTF-8 code for the "em dash" (—). This table by Roy Reed lists a bunch of entities by name (when one has been assigned), decimal number, and hex number and shows the results in your web browser for each of them. Unlike some other tables you see out there, this one is based on UTF-8, which is the character set we have the fewest problems with across platforms.
HTML Dog
A "good-practice guide to XHTML and CSS". Tutorials, references, and a blog. [RSS Feed]
A Tutorial On Character Code Issues
What does <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> mean? What's the difference between UTF-8 and LATIN-1? Does it matter? This tutorial by Jukka Korpela, with some very nice external links, is a relatively painless introduction to character codes.
Resources For Web Design
Just a pile of bookmarks (in fact, the directory name in the URL is "favorites"), but a big pile of bookmarks on all aspects of Web building.
Brainstorms and Raves Articles
Shirley Kaiser's articles from her blog on semantic markup (links toward the bottom of the page).
Tutorial: Character Sets and Encodings
A tutorial at the W3C about character encodings. It also has a good summary of browser "quirks" mode.
Authoring Techniques for XHTML & HTML Internationalization: Characters and Encodings
According to an old friend, the only significant question in life is what to do next. The Web is full of theoretical discourses on character sets, but you'll have to search hard to find out what to do: first do this, then do that, and so on. It's still a working draft, but this tutorial at the W3C is the best we've found for learning what you have to do, step by step.
Felix's Own Web Authoring Topics & Tools
You can specify sizes in points, pixels, ems, percents and probably furlongs. But which one to use? Felix has a huge number of examples to bring light to the darkness.