Channellocks
Before I got married, some friends planned a "Tool Party" for me. This was a great idea because I had nothing in the way of tools. Outside of a screw driver set, the most useful gift that I was given was a set of Channellocks.
Now, I'm still not a "Mr. Fix-it", but I'm certainly better after nearly eight years of marriage than I was in 2007. My set of Channellocks remains one of my favorite tools. It's one of those tools that you always seem to use to get yourself out of a jam with a stuck screw or other random situations. While Channellocks are technically a type of slip-joint pliers, the brand name has become so synonymous with the tool that it's the Kleenex effect. If you are just starting a tool collection, a good set of Channellocks would be a great addition.
Get a set on Amazon for $28.31