FamilyRelatives has added "100 million" records of British overseas births, marriages, and deaths. (Can it really be that many?) These are scanned images of the General Register Office indexes, not transcribed, searchable by index type, date range, and surname range. For example, you don't search for the birth of John SMITH in 1874. Instead you select "Search", then "Overseas", then "Births", then (for example) "GRO Consular Birth Indices", then "1871-1875", then "S", then "SKENE Ralph Rangabe - SMITH William Rait". And then, if you have the right viewer installed, you see an image of a handwritten index that includes volume and page references for SMITH John (registered at Constantinople) and SMITH John Salmon (registered at Alexandria).
Yes, this is a clunky interface that could be (and should be) improved, but it's free, and it's not available free online anywhere else. (Update: The same data are available for a fee at 1837online.)
Dick Eastman's EOGN blog has posted more information about these records from the FamilyRelatives newsletter.
Three tips: (1) You have to register to use these indexes. On the FamilyRecords homepage there's a link to "Overseas Records", and links from that page to further information about each of the overseas BMD indexes. But this is only explanatory material. To actually search, you need to register and log in, and then a "Search" tab will miraculously appear. (2) From the Search tab, choose "Overseas", not "BMD", which would take you instead to the more familiar civil registration indexes for England and Wales. (3) Viewing the images requires the free DjVu browser plugin. If you don't have this, you won't get an error message, you just won't see any images. If that happens, click on the "Help" tab and choose "DJVU Plugin" for instructions.