A port of rikaichan for chrome. Translate Japanese by hovering over words.
rikaikun allows you to read Japanese web pages by hovering over words you don't know and getting their translations.
Activate the extension by clicking on the 理 in the top right. When the introductory pop up appears, rikaikun is ready for action.
When it's activated, when you hover over Japanese words they'll be translated in a pop up. If you hit shift/enter, you'll see some information about the first Kanji.
Press 'd' to hide the English definitions; press it again to bring them back. (Also changeable on the Options page.)