PopClip - iOS Copy and Paste for Mac
PopClip is a Mac application that turns copy and paste on your Mac into the same pop-up style as on your iOS device.
It's available from the Mac App Store for $4.99 or you can download a free trial from their website that has a neat method of expiring: you get 150 uses of the app before you have to buy it.
Set the size, whether you want it to open links or not, enable dictionary loop up or correct spelling:
Disable PopClip from running in certain programs:
How many uses you have left:
Interesting idea for an app, particularly one that you could certainly see Apple doing themselves down the road as more and more of iOS makes its way into Mac OS X.