Best plugin ever
I use Safari as my regular browser, mostly because Firefox’s very un-Mac-like interface really bothers me. I do miss some of the better plugins though - like the one the blocks Flash files until you actually want to see them.
Now, Safari has one like that: ClickToFlash. http://code.google.com/p/clicktoflash/
EDIT: It’s moved, and the old Google link is invalid. Now hosted at GitHub: http://github.com/rentzsch/clicktoflash/tree/master
Rather than instantly loading and running Flash files, the browser shows a grey gradient. If you want to see the Flash, click the gradient, and it will then load and play.
Benefits: Fewer ads, less visual clutter and way way lower memory usage.