Blue is my all time favourite colour. In fact I painted my room blue when I was a teenager, Hugh's room is blue & when I have a daughter, I think her room will be blue too (at this stage anyway!).
It's such a versatile colour (really I thinks it's the paint colour equivalent of the little black dress) and it's various shades can be used with so many different colour combinations. Check out some of these gorgeous nursery's (sorry I didn't make a note of where any of them are from but think most are from here & here).