Well there's more to do, but an alpha version of three services is now there if you want to play. All of them currently put out only XML, no JSON or raw text, GEDCOM or whatever else, but this may change and new services may be added. Have a read here. There is an events database, publications from our Archaeology Service, and a sort of geocoding tool. I've rejigged the code so that adding a different (XML) output format to these involves just writing XSLT and putting in a new value for the "mode" parameter, rather than fiddling around with C#, recompiling and all that. All feedback most welcome. But don't bug me about a collections API!
To start you off, here are links to one request from each service.