The most recommended book on these boards seems to be Physical Medicine & Rehab Secrets. Personally I liked Essential Physical Medicine & Rehabilitation by Cooper more, but that's just me. Amazon offers a "view it now" for both books--take a look at what suits your style more. Keep in mind you might be able to borrow one/both from your library.
PM&R Pocketpedia by Choi is great for rotations. Fits real nice in your coat pocket. Every resident you work with will have it.
And don't forget a decent reflex hammer... Definitely get something better than a Taylor hammer.