Ecology / Environment: Subscribe to the ECOLOG listserv. You can set your subscription to receive one email daily that contains a digest of all posts to the list. Posts range in topic, but will include opportunities for biology students.
Wildlife-related jobs around the country: check out the "Texas A&M Wildlife Jobs Board" or the Jobs page through the national chapter of The Wildlife Society (http://wildlife.org).
Physiology: The American Physiological Society has descriptions of careers availble to physiologists.
Government jobs in all biologically-related fields can be found by seraching http://www.USAJobs.gov