SnapRuler 1.1.1
First, hitting shift immediately snaps the measuring rectangle to the nearest visible edge (like the border of a button or window). Second, once you’ve measured something, you can copy the values as CSS or Objective-C code, and directly paste them into your text file. And third, you can easily resize your selection rectangle by single pixels using the arrow keys (something I have to do often when I’m working with a trackpad).
It’s a nice little app. There’s no trial version, but it works as you’d expect.
