Arduinos are pretty cool: the thread!

[Rococo Modem Basilisk]

If I wanted to control my toaster, I have this timer-socket thing I sometimes use to make my coffee machine start 5 minutes before I wake up. Since you have to fill the damn thing (coffee machine or toaster alike) before it's any use to switch it on anyway, any more complicated behaviour would not be very useful.

What if you wanted your coffee machine to make hot coffee before you wake up when it's cold, and iced coffee when it's warm? That would be an arduino project.

I think most arduino users just play with it, though. Otherwise, it would be marketed towards businesses rather than hobbyists. There are useful things you can do with it, but many of the useful things are either redundant, not at all fun, or both.