Jim Breen's Japanese Page has lots of interesting links. He is the author of several tools on which JGloss is based and is the iniator of EDICT and KANJIDIC.
The Wadoku Jiten page offers online search in the Japanese-German dictionary. You can also help improving the dictionary there.
Two WWW interfaces which provide glosses for any Japanese web page without having to run an extra program: Todd Rudick's RIKAI server and Jim Breen's WWWJDIC.
aedict is an open source Japanese dictionary app for Android (project page).