Getting certified for a different area then the one I work in?

Hi all,
I am just finishing up 2 years of NICU experience, but it looks like I will be switching over to becoming a PICU nurse. I know I have to get 2 years experience in PICU to take a Peds Critical Certification, but should I go ahead and get certified in Neonatal nursing? My hospital offers a bonus for those certified, has anyone had experience with being certified in an area other than the one you're currently working in? Thanks.
I think it would be a good thing. Makes you more appealing to employers. You just never know what could happen.