Listservs
The CRTNET listserv page maintains an archive of CFPs, Fellowship Deadlines, and Position Openings, as well as information about signing up.
H-NET Discussion Networks cover a wide range of research areas in the humanities.
"ECREA [European Communication Research and Education Association] members and non-members alike are welcomed to subscribe to this information resource."
Associations
The American Rhetoric site maintains a fairly comprehensive list of other communication associations (not just rhetoric), as does the Scholarly Societies Project.
Job Listings
The Chronicle of Higher Education
Academic 360 is a meta-site that posts links to other faculty position listings, as well as links to Job Posting pages at universities by geographic area.
Conferences and CFPs (general)
Conference Alerts posts Conference Announcements and CFP deadlines arranged by discipline and then date
General Advice and Portals
Professor Jonathan Sterne at McGill University maintains a comprehensive guide to the job market for new PhDs.
The Media Research Hub (SSRC) contains an interactive Resource Database where you can find projects, places and people in your interest area. The Data Consortium serves as a clearinghouse for datasets and research results in media and communications. The site also posts information on their "Bounty Project" and other collaborative grants.