We've all got one thing we use all the time which we picked up on the street or found somewhere. Yours might be that old but expensive hifi component you rescued from the dump, or something like that.
Mine is a server rack power strip i found in the rubbish at work some time ago. This is a metal bodied thing with 16 power sockets - it's been on my desk at home for a few years now and makes it easy to play around with various bits of kit.
What's yours?