I used the books i got from EMRA to keep in my pocket... the ED Guide to Antibiotics and the Top 30 EM Problems... also I kept Maxwell's, pocket pharmacopeia, and a notepad in my pocket... although those are always standard. I didn't really feel the need to keep anything else in my pocket. Try to keep a pair of trauma shears on you, too, you'll look like an angel if you can show those bad boys.
The EMRA books are great -quick easy and simplified, great for students. The antibiotic reference will also be of value in residency.
Currently in EM residency and love the Tarsons EM reference book. Same company that makes the pocket pharmacopia. The pocket book is amazingly inclusive and has references for every fact (EBM). Covers most major topics in em. They also put out a Peds EM, ICU, Ortho. I carry the EM, and Peds EM.
Sanford is another must have.
For the palm dorks, I most frequently use 5min clinical consult, epocrates, epocrates qid, and med calc. there is a 5 min em which is useful also.
If you can get some of the above mentioned trauma shears from the pharm reps.
The above reference is to TARASCON's EM pocketbook.
Certainly a favorite. The pocket shears can be bought at a hardware store or even a "Big Lot" type store for a couple bucks. The go under the name "utility shears".