In the wordpress theme I prefer (link here to original), I hacked in lots of purple.
Then I wanted to change the right column width. Eww — it was using background images of a fixed size to color the left and right columns!
Pulled out those background images, and replaced them with color strings ala #666 and #ccc.
Then, the columns on the left and right didn’t go all the way down, and were never balanced with each other nor the center column.
Finally, I found some javascript (which can be loaded in a separate file) — Balanced Columns and from there, this page.
The really good news is that it locks up IE. Yay! OK, disable that for ie, and add a “get firefox” link to the links.