Jim Breen's WWWJDIC Japanese Dictionary http://www.aa.tufs.ac.jp/~jwb/wwwjdic.html http://www.rikai.com Denshi Jisho — Online Japanese dictionary http://www.jisho.org/ (if you can understand the Japanese on the page) http://www.alc.co.jp/

the fastest way for me is the dictionary that comes with the freeware japanese text editor JwpCe. It works both ways, JAP<-->EN and EN<-->JAP

Also VERY useful are the Rikaichan and Moji addons for Firefox and Thunderbird.

I use online dictionaries. dic.yahoo.co.jp and http://www.csse.monash.edu.au/~jwb/wwwjdic.html

I always use 広辞苑