2010-01-10: I don't know how easy or hard this is to implement, but I second the use of Markdown in the site: it's easy to write, and it's made to produce valid HTML. Practically all my writeups of the past few years have been written in Markdown and then passed through pandoc to produce the final result.

Curiously, the simple combination of Markdown with pandoc produces HTML with more features that this site allows to its users, namely:

• Header references, so that it’s possible to link to a defined header on the same page,
• An easy syntax to create and display footnotes with internal links to its corresponding section and back,
• Easy conversion, if needed, to proper typographical signs: straight "quotes" become “curly quotes”; two dashes 3--5 become an en-dash 3–5; three dashes --- become an em-dash—like this one—that’s easy to write. And three dots become an ellipse… Granted, some of these can mess up with node titles, but it's relatively easy to toggle these options on and off

2010-01-11: Also, it would be great to have proper support for mathematics (via MathML/MathJax). Current support is barebones and noders of past (and present) had to make do with <pre> tags and ugly ascii constructs for things like fractions and integrals. This place needs more actual mathematics.