I read, well, try to read, to my son daily in Japanese. And before we decided to hold off on the third language, my husband read to our son in French.
I found a few bilingual books and thought they would be fun. I envisioned me reading it in Japanese to B, and my husband reading it in English. (Most of our Japanese books are just in Japanese, so when my son brings those to my husband, he's out of luck).
We have Where are you going? To see my friend! By Eric Carle & Kazuo Iwamura, which I bought off of amazon.ca. I also found it in the children's section of the library, right in with the English picture books, so perhaps it is available in other libraries.
This is a great book. It has the romaji next to the hiragana, which I confess I use a lot because I default to reading the alphabet. The story is cute and the English and Japanese are the same story, but because it is two friends meeting, the English goes from one end of the book and the Japanese goes from the other and the two friends meet in the middle.
We also have Too Many Pears by Jackie French. I bought this at a bookstore (World Kids Books) in International Village that has books in French, German, and a few other languages. It only says French and German, though, so I was pleased to find a few Japanese books.
This book has a funny story. The English is directly under the Japanese, so it's easy to see the translation. It is a bit harder to read because it uses kanji and I don't know very many kanji.
This week the book I ordered off amazon.ca, Am I Small, by Philipp Winterburg arrived.
It's very cutely illustrated. Each page has romaji, hiragana, and the English on it. It's available as a bilingual book in quite a few languages, actually. My son didn't find it as appealing as the other two books I've mentioned, but it's a good addition to our little bilingual library. I think I will find it useful for vocabulary building.