for those of you on Mac OSX, using Safari, there's a great little freeware add-on called "Acid Search". I'll see if I can find an url, but here's a screenshot of what it does. I can double click a word and do a right-click search of just about anywhere, including OneLook. pretty neat.

http://www.rogergrow.com/image/acidsearchsm.jpg

here's the url for AcidSearch:
http://www.pozytron.com/acidsearch

formerly known as etaoin...