I guess it would depend on your speciality or what you are interested in pursuing. For example, AORN (Association of periOperative Registered Nurses) has an annual conference every year. You can visit their web page to find info on this year's or future dates. This year's is April 21-26 in Anaheim, CA. And, YES, students can attend free (that is, registration is waived). Usually, we have anywhere from 8-14,000 in attendence. This includes the sales representatives which show their products for part of the time.
ANA, ASPAN (recovery room), urological nurses association, orthopedic nurses (naon) all have annual meetings also. I'm sure other specialities do also, these are just the ones that come to mind.
Website for AORN is www.