Safari Enhancers
I’ve mentioned using PithHelmet. One of the most annoying remaining behaviors in Safari is that the close button closes all your tabs, and its very close to the minimize button. D’oh! Holy usability errors without a warning batman!
Taboo comes to the rescue, adding that warning.
(While I’m blathering about my web browser, let me also mention Sogudi, which makes the URL bar a search space.)
While I’ve never seen the point of tabbed browsing (hooray, you can open two pages at once but can’t see them at the same time), you might look at Shiira. It uses WebCore, so renders the same as Safari, even using the same bookmark database, but has some extra features. Not sure how it handles closing windows with tabs. It’s written by a Japanese guy, so the English on the site is a bit broken (but it’s better than my Japanese).