I recently read this article about just how awesome the Webster's dictionary is compared to other dictionaries.. I highly recommend it.
After reading that I installed that dictionary in OSX. Then a few days later I needed to look up a Japanese word. I usually go to WWWJDIC to look things up but it's annoying to have to be online.
Then I got to thinking, Hmmm, if I was able to install a dictionary into OSX I'll bet there's a Japanese or Japanese to English dictionary. A few clicks later and BAM!, turns out there's one built in. All you have to do is turn it on.