Earlier today I found a strange little app called Pith, which provides a floating window menu for Safari. Now, that doesn't sound very impressive, but given that it hides when Safari isn't frontmost, and that it's fairly configurable (you can change how it orders windows, and whether it shows up in the Dock) it's damned useful.
However, Tom really found it useful when Safari crashed and it maintained his current window state, so he could recover his session. Also, for those of you who like tabbed browsing (and no, I don't) there's an option to open windows within the same frame (which I haven't tried).
Like PTHiTunesNotifier, it's a sign of how far you can get with a decent IPC mechanism (in this case, AppleEvents). And, of course, Perl can speak them too, directly or via AppleScript. Which is nice.