When I first got out of school I download every nursing app but since I have been working these are the only ones I use.
Apps I use every day in the ED
Calculator: just the crappy one that comes with the phone works fine.
Drug guide: I use Davies from Nursing Central but when it is time to buy again I will get it from skyscape (the company that owns NC is on my stool list). Epo is fine, Micromedix is good.
Calendar: "oh crap I have to work tonight"
Apps I use once in a while
Tabers: mostly for spelling, google also works
Google translate: when I need to tell the pt to pee in the cup and I dont want to go get the blue phones.
Lab values: when the Doc orders so funky lab or I have a brain fart.
Mooncast to tell what kind of night I am going to have.
Timer: remember to get that 4hr tylenol level on that OD