The American Astronomical Society (AAS) has information on currently available postions in astronomy and astronomy related fields. The AAS also publishes a useful brochure (available in electronic form or by mail). See AAS Career Services for additional information and links.

AAS Monthly Job Register (Current and previous month job announcements)
AAS Job Listings (Links for various job situations)
Industrial Astronomers Network (Non-traditional jobs)
Summer Employment (for undergraduates, graduates and postdocs)
AAS Careers in Astronomy Brochure (A New Universe to Explore)

Printed copies of above AAS Careers Brochure available by writing to:

Career Brochure, AAS Education Office,
University of Chicago,
5640 S. Ellis Ave., Rm. AAC 112,
Chicago, IL 60637 USA

(Please send a stamped, self-addressed envelope.)

The Professional Astronomer (produced by the Astronomical League)

(Also check out the American Institute of Physics web site for career information.)