you do not have to break the bank to have a decent working library. for your first couple of years of practice you'll probably be fine with your med/surg texts and other references from school to go back and reread prn when you have a new kind of patient to work with. when a specialty chooses you (note: that's usually what happens, rather than the other way around-- all of a sudden you find that, oh, endocrinology or something has stolen your heart away) you will want to get some books on that to deepen your understanding, and by then you'll have learned enough that you will be able to learn more in depth about it and want to join the nursing professional orgs that work with it.
for general purposes, not counting my specialty books, i couldn't do without the nanda-i, most current edition, joyce lefever kee's absolute classic laboratory and diagnostic tests with nursing implications, and the 5-minute clinical consult, a sort of a reader's digest condensed of a bazillion diagnoses with shorthand reminders for everything you need to know about them. there's a taber's in here somewhere, and a gray's anatomy (the book, not the video). i also have the chicago manual of style and the slim, short, and sweet strunk & white's elements of style to help me when i forget how to write clearly.
i use books, not online sources for all these things, because generally when i need to look something up i need to use it right away, and i do not want to tempt my wandering brain with another link and another link and before i know it i'm playing angry birds again.
