Apple iTunes Store's iTunes U and Podcasts area are two great places to learn new things and that begs the need for having a Dictionary handy to lookup all those new words that are coming at you, especially if you are a non-native-English-speaker. Here's one way to gain fast access to Apple's Dictionary app from iTunes:
echo 'tell application "Dictionary" to activate' >> \
~/Library/iTunes/Scripts/Dictionary.scpt;open \
/System/Library/PreferencePanes/Keyboard.prefPane
This will create a simple script for you, then open the Keyboard Shortcut panel of the System Preferences. Assign a shortcut to your new menu title -- Dictionary -- in the application iTunes, and you are done. Next time you launch your iTunes you should have a Dictionary button, under the script menu, ready to work with your assigned hot key.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20071022114114578