Customization is working pretty much the way I envisioned it. I have twelve themes now, some based on other site's color combos (as an homage, not a ripoff). I have all the nonessentials removed and this site loads pretty damn fast.
Themes now encompass link colors as well as page backgrounds. Picking appropriate link colors is really hard. I didn't think custom link colors were doable, but the document.styleSheets[x].rules.item(y) gives me access to the entire stylesheet by rule. Sweet. Seems to have a bug setting the background color of a DIV, though. Technology. Eh.
Themes now also encompass scrollbar colors (yawn). This breaks my CSS validation. I may yank scrollbars out, because it's such a non-feature. But for now I'm yanking the validator links.
All the 88x31 buttons at the bottom of my page were introducing a noticeable lag before my floater menu went into motion, so they're gone. I have text links for the HTML and CSS validators, plus a text link to greysoft. (Thanks, Noah. Greymatter is unbelievable.)