I stumble across free resources all the time, and hope to make a comprehensive list here.
I have found two brilliant resources in the past week for family history:
The British Genealogy forum, which has a “Brickwalls” section for people who have come up against a brickwall in their research.
That forum has a section to allow people to offer certificates which they have ordered in error. That’s also a service on offer at the Certificate Exchange which is becoming a wonderful resource too.
For information about Clergy in the Church of England, I recently discovered a great free resource, the Church of England Clergy database.