[seltzered]

I've experimented with tabs on the side for a while (tree-tabs in FF, and vertical tabs in chrome). While side tabs work nice when your browser consumes the whole screen, I usually work by having two browser instances (one on the left, one on the right) instead. At that point, horizontal screen real estate becomes more crucial.

I figured aza's tab candy (panorama) is really the nice compromise in letting you organize tabs (a la treetabs). It just needs to be refined to where it can be set as the home page so you get used to that workflow.