An off white/ivory.. and use a lot of greens browns yellows oranges.. or if your decor is going to be more simple then you should probably do the walls a brighter color.
Cream with wood furniture and giant wall sticker
We've done our nursery with a jungle theme and gone for yellow on two walls and white with pictures on the other two :)
Green yellow or brown I would say :). Google and have a look at other nurserys with the same theme.