I use both Windows and Mac OS X on my work/home computers, and on Windows I love SnagIt, because it allows me to capture fixed regions of the screen: I select a resolution (for example, 500x400), and then when I click on the capture button a rectangle with that fixed dimensions appears on the screen. I only have to move it to the exact location of the screen where I want to make the capture and it's done.
The capture utilities that I've used on Mac OS X (native, or Jing, for example) doesn't have this feature afaik.
Is there some way to have this kind of feature in Mac OS X? Any utility that could add this to my day-to-day?