Ever wonder what the original universal tool might be?
It just may be the file.
Beyond the obvious purpose to either smooth or file metal, plastic or wood to shape consider you can also:
1. Cut material to length (using sharp corners)
2. Hammer nails or brads - provided it's a beefy enough file
3. Use it to pry two or more boards apart
4. Open a can of paint with it
And, of course, once the paint can is open, you can work most efficiently by using it to stir the paint.
I'm starting a new trend here, that I hope will catch on. Despite my known tool-alcoholic tendency, I'm turning over a new leaf - I think I can get by with two or three tools -
something that makes holes, such as a drill; drives screws (hey, a cordless "drill" also works - even more efficiency!) and, of course: