http://www.docracy.com/tos/changes http://www.docracy.com/tos/changes provides part of this. They constantly crawl the various terms of service for popular site

http://www.docracy.com/tos/changes http://www.docracy.com/tos/changes provides part of this. They constantly crawl the various terms of service for popular sites and generate diffs. Using something like that it would be pretty easy to get an email every month of the things that have changed in services one uses.