Essex
http://linux02.lib.cam.ac.uk/earlscolne/contents.htm - Earls Colne (a huge and long-running project which tries to tie together every person and place mentioned in Earls Colne records)
Essex OPC -
http://essex-opc.org.uk/
Most Essex Parish Register images now available on Essex Ancestors:
Essex Ancestors
And many are indexed on FamilySearch.