Harriet Lane and Pediatric Dosage Handbook were sources I used during my rotation there. PDH is through Lexicomp and generally if you have a sub for it, you can find the information online, although I've not been in a peds or nicu ward that didn't have a couple of copies around.
One that I didn't use was the Teddy Bear Book (ASHP), mostly because it was only IV. Nelson and Lange have books that are more medically orieneted but were interesting reads.