With whole websites dedicated to uncovering the nuances of OSX, it’s no wonder that interesting tidbits are popping up all the time. Any OSX savvy user that follows the cult of tycho will find this discovery from Silver Mac’s “Cool things you can do on a Mac” incredibly helpful:

When in any of the Cocoa (Mac native) applications you can hover your mouse above the word and press Ctrl-Cmd-D on your keyboard. You will get the Dictionary description for that word.

So far this is working great for me, with the only caveat being that you need to hold the Ctrl-Cmd-D keys, as the Dictionary entry vanishes upon release.

Go forth sweet Mac users, and fortify your knowledge!