Until I found this site, I never really considered certain sounds to be "endangered" in the same way as, say a coral reef or something. But the more I looked (and listened), the more I understood what the author of the site was trying to do.
I'm certainly not nostalgic for the beep-boop-screech of an old-style computer modem or the start-up music for Windows 95, but these are sounds that were part of millions of lives for many years.
If I had one request, it would be for the ka-CHUNK an 8-track player made when it channel tracks. Again, I don't miss it--I never even owned an 8-track machine--but I think such a sound would be constructive when trying to explain to future generations the crap we used to put up with to listen to music.