DS was two and three quarters. DD got him a wooden train set. It was SUCH a good idea. The novelty lasted a few weeks straight and really helped distract him in those early days. Plus it was easy for adults to play with him with it when they came to visit/help (because you do worry about neglecting your older one a little).
I just asked him now who gave him the train set (6 months later). He didn't actually remember it was from DD, but I don't think that is the point. It was just something exciting for him (because he didn't find the baby that exciting) that kept him distracted when we were absorbed with the baby. It kept the peace.
And it is still a much loved toy.