Try using tree style tabs, it's really great. Most websites are laid out such that there's tons of wasted horizontal space and vertical space is limited, so you increase usable screen space by moving tabs to the side. Additionally, with tabs at the top, the more tabs you have, the harder they are to read and keep organized. With tree style tabs, no matter how many you have, they're always maximally readable, and the ability to nest them and collapse groups gives you a ton of power organization wise. You can also easily hide the sidebar when you DO need the extra horizontal space. The ability to bookmark groups of tabs at once makes it much easier to keep close tabs you aren't actively using.

We spend so much time using web browsers, why not optimize them for human use?