I recently discovered that the poplular statename sample XML-RPC service at betty.userland.com is no longer available, so I'm making available some sample XML-RPC services here. The first is: Test Math Service. Over time I'll add some more so that people can exercise their XML-RPC client writing skills.
There still seems to be some interest in XML-RPC. I'm seeing roughly 5000 downloads per year of the XML-RPC.NET distribution. There are also the various aggregators, blogging engines, and blogging clients which use XML-RPC.NET.