The list below is certainly not exhaustive. However, I did find them to be both informative
as well as relevant to IS majors.
The American Political Science Association has good information on career issues,
as well as helpful advice on graduate programs. http://www.apsanet.org/section_413.cfm
UC Berkeley and Johns Hopkins provide very helpful "career exploration" sites, complete
with numerous links and information about careers as well as graduate programs. The
"sector profiles" section at the bottom of the JHU page contains a very detailed breakdown
of possible career paths.
The Foreign Policy Association as well as devnetjobs.org has postings for jobs and
internships. They also offer newsletters on employment opportunities. Idealist.org
also has jobs postings with nonprofit organizations.
There are a good many "generic" job sites that have a wealth of information about
general job-hunting strategies (i.e. letter and resume writing, interviewing tips)
as well as job postings. Though they are a bit overwhelming in that they are aimed
at the broader labor force, they are still useful. You may need to play around with
different search terms to find jobs for which you are interested/suitable.
America's Career Info-Net provides general information about U.S. job market and future
trends. Other worthwhile "generic" job cites include the American Marketing Association,
the International Association of Business Communicators, OverseasJobs.com, The Occupational
Information Network, and The Riley Guide.
Bright.com helps you to connect your job search to your family, friends and alumni
network. Bright's job seasrch engine shows you what jobs are available at companies
where your friends work. Finally, monster.com offers a huge database as well as useful
"advice" section for numerous industry sectors (including government).