When Apple announced they were bringing iOS features “Back to the Mac” with OS X Lion (and doubled down on it with Mountain Lion), the iOS implementation of copy and paste was not included.
PopClip is a clever Mac app that brings iOS-style copy and paste to OS X, and raises the question of why Apple hasn’t done this already. If you’re curious as to how well it works, the answer is: pretty well. The most common sentiment in the user reviews is: “I’m hooked.”
If you have a Mac, you should check this out. You can download a free demo at Pilotmoon Software. The full version costs $4.99 on the Mac App Store.