Google Custom Search Engine:
As at March 31st 2013, there are 437 sites built into the custom search engine.
OpenSearch browser plugin section active

Database (Site List):
Public view and RSS feed status: active
Twitter feed status: active

Updates will be issued quarterly

If you have any feedback or suggestions, please contact admin@ahdb.org

Kind Regards
H Niyazi
B.App Sci.
AHDB Administrator