Are there sites where I could find out about which universities and
colleges have journalism professorships available?

Dear  pranaygupte, 

There are several academic vacancies sites, that will give you a
picture of the vacancies available:

Jobs.ac.uk
<www.jobs.ac.uk> - mostly UK/RoI jobs; 

Times Higher Education Supplement
<http://www.jobs.thes.co.uk/> - mostly UK/RoI jobs; 

H-Net Job Guide 
<http://www.h-net.org/jobs/> - mostly in the United States

Higher Ed Jobs
<http://www.higheredjobs.com/> 

Chronicle of Higher Education
<http://chronicle.com/jobs/> 

Academic 360 
<http://www.academic360.com/> 

I hope this answered your question. Please contact me if you need any
clarification on this answer before you rate it. My search strategy
has been to look for academic job website.

Much appreciate the researcher's effort. It's very useful indeed.
Thanks, Pranay Gupte

Thank you for the rating and the tip. I hope you'll find a good position!