Hides the sidebar because it takes up too much screen space for me, especially in Vertigo.
I actually do like having the sidebar around though, so I wrote a Greasemonkey script that will move the sidebar to the top: http://userscripts.org/scripts/show/11244.
I'd recommend using this CSS in Stylish in conjunction with that script -- this in Stylish to avoid flickering (because it doesn't have to wait until all page content is loaded to be applied), and then the Greasemonkey script to get the links on top.
.ad {
/* Your ad can be here instead. 10K unique visitors for $5/day. Mail me. */
}