iKnow.co.jp

For those of you who study Japanese (or want to start studying Japanese!), I found this site to be very useful.  Also, to aid in understanding Japanese e-mails or webpages, I use Jim Breen's site quite often.  All you have to do is copy and paste in the Japanese text and accurate readings & definitions come out to help you.  This may not be the the best for people with only a beginner's knowledge of Japanese however.