If you own a Palm or PocketPC, PEPID is not to be missed (
www.pepid.com). Think of it as a better version of the 5 Minute Emergency Consult, Epocrates PRO, and every medical calculator you'd every want plus an eye chart, etc rolled into one. Yes, you have to pay for it, but it's updated every 6 weeks or so, and they do offer a resident discount (the last time I checked). Everybody I've gotten to try it has loved it as well. It's the little things it has like the dosing calc built into each drug which rocks when you're treating kids as well as the "Dispo" guidelines in each section which really help when you're dealing with something unfamiliar.
And, most importantly, "Don't Panic!"