It's very difficult to generalize about post-graduate requirements because of the many options available to Biology majors. For students planning to go on to graduate school, be aware that many programs require 2 semesters of Physics, as do medical and many other professional schools. Look into the requirements and recommendations of the sorts of post-baccalaureate programs you're considering.
Depending on your interests, courses in economics and statistics may also be helpful. With the ever-increasing flood of opportunities in bioinformatics, some experience with computer science is becoming increasingly advantageous.
The National Human Genome Research Institute has a new website up which is a great resource for anyone interested in a career in genetics or genomics. It has a dozen video interviews with scientists who've followed all sorts of career paths, descriptions of many career possibilities, and links to many other online resources.
The Ecological Society of America Home Page contains a wealth of information about the society, especially information about how to join and career/job opportunities in the field of ecology.
ECOLOG-L is the listserv operated by the Ecological Society of America. If you sign up you can send and receive e-mails from all those who subscribe to the list. Of special interest to students are the many announcements of summer internships and graduate school opportunities that faculty sends from around the world who are looking for students interested in studying ecology. This is a "must" listserv to join if you want to do a summer research project or go to graduate school in ecology!
Beta Beta Beta (more familiarly known as "Tri-Beta") is a national honors society for majors in the biological sciences. Any student who has completed three biology courses with a B or better in each and has an overall biology GPA of 3.0 or higher is eligible for full membership. The Rho Eta Chapter at Moravian College actively promotes undergraduate research and organizes various events for the student body. Information on these events will be available at biweekly meetings.