My 3rd post in this forum
it.
I do not know if this is similar to rikai.com, but there is an add-ons for firefox name rikaichan, it is the best add-ons for those who are learning Japanese.
1. it give you furigana (how to read kanji in Japanese)
2. it give you meaning to kanji , hiragana, katakana
3. it give you description of the words
4. but to use this you must able to read kana. of course the description and meanings are in English.
this is the add-ons (only for Firefox tho)
Rikaichan add-ons