Smart tools as xScope 2 make me feel sorry sometimes, that I don’t own an Apple Mac! ;-)
If you work on a Mac and do (web)design, I recommend you to drop a look at Doug Bowman‘s blog, where he wrote a detailed explanation about xScope (in short, this is something like Screen Calipers, multiplied by 10… or even 100!).
Argh! This is called Win-discrimination! :-D