Well there aren't demos at the TZX Vault just yet, but I got an email from Steve who runs it, saying he'd be happy to post any demos you may have on the site.

" It would be preferable if they were in .tzx format, but failing that I'll accept .tap as I can master tapes from .tap files and create .tzx files from tape masters. "

I think that generally, standard-loader demos wouldn't be needed (these can be picked up from Demotopia). But I mentioned the other day about a non-standard tape-loader by the Israeli Team. This would fit well as a pure tape image at the Vault. I'll have a dig through my old tapes and see if I can sort it out. Any others people know of?
So if you have some non-standard tape-loader demos, create .TZX's and send them to Steve. Instructions on conversion can be found on the Vault, and also some unrelated information on attaching a 3" drive to a PC. Wish I'd known about that one earlier.