I use Lazarus a lot on Chrome and FireFox. Well, not a lot, but it's great for crashing when you're writing something online in a form that doesn't automatically save what you're writing. Plus, this should be default in every browser ANYway, and not built-in any web site (such as gmail).
So, is there any such option for Safari? Does Saft do that? Just by looking at the home page, it seems to me like bloatware to Safari 4.