Easily Look Up Japanese Romaji, Hiragana, Katakana and Kanji
RomajiDesu is a great tool for Japanese learners. This website allows you to search for Japanese Romaji, Hiragana, Katakana and Kanji (characters) and find the English translation.
The website also allows you to search for the Romaji equivalents in Hiragana and Katakana.
An audio pronunciation example is available for the words you look up.
Also of note is a light mobile version of the website and a browser toolbar for quick and easy translation of any highlighted word on any webpage.
All in all it's an easy, free online English-Japanese-English dictionary and toolkit for Japanese learners!