Where did the digital color meter go in Yosemite? I used to have the Digital Color Meter (system app) in my dock, but since updating to Yosemite it doesn't appear in the dock anymore ("?" sign)
Did they just move it and Dock cannot find it?
You can find it under Applications/Utilities.



From there, you can drag it to your Dock to create an alias.  See Mac Basics: The Dock for additional info on making the most of the Dock.

To remove the Question Mark, drag it off the Dock until you see "Remove" then release.