Something a little more 'retro' from Peter Howkins...(I am big fan of RPCemu by the way)
It's a picture of a RiscPC/A7000 build of RISC OS from the ROOL sources which is 26bit compatible, which might be useful for being an unambiguously freely-licensed version for use in current and future emulators.
It mostly using the code from about 2002, being roughly 4.0X-4.1X in terms of features, and suffers from a bit of an identity crises :D