I was a bio major, we were introduced to it first in my genetics class... It's an awesome site to use when doing research or literature review papers, especially the PubMed search tool. I always started any research paper or assignment by gathering info at this site.
I passed it on to a friend who is a grad student in Social Work... they have to write an obscene amount of papers in that program, and I showed her how to search PubMed for articles... She LOVED me for it.