For those who are already unfamiliar with Ninja words, it's probably best described as a Web Too (sic) on-line dictionary. Fast, no ads, clean interface etc. etc. While the definitions are not the greatest in the world (they are scraped from the Wiktionary project and other free resources), they are good enough for a quick look-up.
While there are search tool-bar plug-ins for Firefox, I prefer to use a bookmark with a keyboard short-cut instead. To do this, do the following:
http://ninjawords.com/%s for location, and n for the keyword.Cool. huh?