If you need any help tracking down binaries and things, feel free to let me know.
You could also possibly gather together some of the weirder ports that MAMEdev was never responsible for. For example: - all files related to XMAME and XMESS - all files related to MacMAME and MacMESS - all files used to be hosted by the MESS homepage
Public mirrors are fading away, though most files survive in the Wayback Machine (archive.org)