Area Guides.net
Churches, temples, synagogues and religious monuments.
http://romeit.ags.myareaguide.com/index.html?CatID=2&SC=36

Chris Nyborg
Notes on the history and architecture of dozens of churches, chapels and oratories in Rome.
http://roma.katolsk.no/alphalist.htm

In Italy
Details of churches where services are held in English, as well as synagogues.
http://www.initaly.com/ads/walking.htm

ITWG
An introduction to Rome's most notable or historically significant churches.
http://document.itwg.com/en_roma6.asp

Knowital.com
A guide to places of worship in Rome, including mosques.
http://www.knowital.com/italy/romeinfo.html

Roman Homes
English language church services in Rome.
http://www.romanhomes.com/your_roman_vacation/religion.htm

Roman Homes
Information on Papal audiences.
http://www.romanhomes.com/your_roman_vacation/papal_audiences.htm