It's always nice to have the right tool around exactly when you need it. One way that you can accomplish this would be to carry a tool box with you everywhere you go, but that can be a bit bulky and somewhat impractical. A more convenient option would be to carry a multi-tool, such as the Victorinox Swisstool RS.
This a very sturdy multi-tool, and some may find it to be somewhat larger and heavier than other multi-tools out there, however, for a full-sized multi-tool, this is one of the best that I've found.
Some folks may choose to carry this tool on their belt with the included velcro pouch, but I leave mine in my car's glove box. From there it's served many purposes, such as using the knife to cut rope, using the scissors to cut wrapping paper to wrap a last-minute gift, and using the knife and pliers to pry a bullet out of the side of my girlfriend's car. (It was a stray bullet that came from a hunter's rifle whe was driving near a field. Thankfully, no one was hurt.)
This tool offers a great selection of implements, such knife blades, various phillips and flathead screwdrivers, scissors, a can opener, and others. And all of those implements can be accessed without opening the pliers. If you're like me, you may not use every implement on a regular basis, but it's sure nice to know that they're there if you need them.