Online Dictionaries and Browser Add-ons

Jim Breen [+]
http://www.csse.monash.edu.au/~jwb/cgi-bin/wwwjdic.cgi?1C

Jisho.org [+]
http://jisho.org/

Mizuho Securities translations of financial and law terms [+]
http://www.mizuho-sc.com/english/ebond/translation.html
http://www.japaneselawtranslation.go.jp/

Tangorin [+]
http://tangorin.com/

Rikaichan [+]
http://www.polarcloud.com/rikaichan/

Space ALC [+]
http://www.alc.co.jp/

Goo [+]
http://dictionary.goo.ne.jp/

Japanese Wikipedia and Japanese Google Image Search [+]
http://ja.wikipedia.org/wiki/
http://www.google.co.jp/imghp?hl=ja&tab=wi (or click on 画像検索)

Tofugu on Japanese Counters
http://www.tofugu.com/guides/count-anything-japanese/