Pixel Tools for Mac

From SOL Robots:

The ideal companion for designers and anyone that needs to make pixel precise measurements, get the numeric value of a color, or magnify a portion of any screen.

Pixel Tools does the following:
1. Tracks the mouse and magnifies the region of interest (1x - 64x).
2. Measures the distance in pixels between two points on the screen (Width, Height, and Straight Line Distance). Y Coordinates can be measured Cocoa style (positive Y is up) or traditional style (positive Y is down).
3. Gives the RGB or HSB numerical value of the color under the mouse (Hex 00-FF, Float 0.0-1.0, or Integer 0-255).
4. Almost every function has a keyboard shortcut so it's quick to access.
5. Keyboard shortcuts have global equivalents so that they can be used even when the app is not frontmost. For example, to set the measurement origin you can use the space-bar when the app is frontmost, and when it's in the background you use Control-Option-Command-Space-Bar to do the same thing. Global keyboard shortcuts can also be disabled.
6. Allows setting the main window to float in front of all other windows for easy access (default), or setting it to behave like a normal window so that it can layer behind the frontmost app. This is great if you want to keep Pixel Tools open all of the time, but don't want it obstructing your view when trying to read your mail.
7. Allows you to hide controls and rulers so that the window can be sized to have a very small footprint, yet still be completely usable. Pixel Tools is designed to see underneath itself, making it so that even when it covers part of the app that you are measuring, it still works. Both of these features are particularly important for users on small screens.
8. Allows locking the mouse position to focus on a particular area on the screen. You might use this to change the color format settings without affecting what the app is focused on.
9. Allows locking the screen updates so that you can measure transient or animated effects. For example, you might use this to measure the distance on an item that has a mouse-over effect. With updates locked, the mouse-over will remain on, while you measure.
10. Works with any number of monitors, of any size, and any layout.
11. Very small executable, so the app launches very quickly.

View larger image