You also can find job information via many professional associations.
You also can use geographically-arranged lists to find out what media enterprises exist in a particular state/city.
For some perspective, here is the latest Annual Survey of Journalism & Mass Communication Graduates, conducted by the University of Georgia.
Commercial service listing internships and summer jobs. Password-protected.
Requires (free) registration.
Database of job listings, plus an extensive list of other job/internships sites.
Extesive searchable lists of jobs and internships.
Frequently-updated national list, from University of California (Berkeley).
Lots of job listings, but you need to register (free) to see details.
Listing of jobs for "media professionals." Provided by Editor & Publisher, MediaWeek, and other outlets.
From the National Association of Broadcasters.
Very lengthy list of job sites.
Geographical and category listings, more.
Job opportunities,from Gannett.