OS X's "Word of the Day" screensaver is a great way to passively learn words:
But I've always thought that its word list kind of stunk—it was full of obscure words that I could never really see myself using. I'd prefer something like Norman Schur's 1000 Most Important Words. What if you could plug your own word list into the screensaver?
On a rather obscure comment thread, someone explained where you might find the word list that Apple uses to power the screensaver. It is at
/System/Library/Graphics/Quartz\ Composer\ Plug-Ins/WOTD.plugin/Contents/Resources/NOAD_wotd_list.txt. The file looks like this: