An HN idea exchange? 
og1: OK here's one that I was thinking of. A hardware compatibility website that lists replacement products, specifically outdated ones that were replaced by newer versions. Some context, about a month ago I was trying to replace a broken garage door opener for a sear's garage door. Well, the Sears line is no longer available and now it is Craftsman. I asked an employee if the new craftsman opener it would be functional, but it was ultimately left up to a crapshoot on if it would work or not. Something like this would be useful for me.