I am just beginning to learn Japanese, and someone passed along a great site that takes a link to a kanji page and it adds kana to it. There's also a Firefox extension (Rikaichan) that provides kana in a tooltip when you mouse over kanji. Needless to say, this makes it easier.
I will mention that a long time ago, I had trouble with the dictionary file extensions being "incompatible" with new Firefox releases. They're just dictionaries, though, so I hacked them to make them stop. They might have fixed that by now.