I have three. One was going to be a home security and automation server, but in the end, every feature it had was either something my family wound up hating, or something that worked 9 out of 10 times and was therefore useless, or something that proved slightly harder than I expected and was therefore too much trouble. So now, all it does is loudly announce the time of various things, like "Time to pick the kids up from school".

The other two pis are sitting in a project crate, ready to use if I ever find myself with extra free time again.