In my front pocket every day (well, except when I'm wearing a dress) is a handy dandy little tool. It looks like this:
It's a Leatherman Squirt P4--a little "fits in your pocket or hooks to your keychain" style leatherman (only 2 1/4 inches long total) with the whole gamut of useful tools like pliers, wirecutters, file, knife, screwdrivers, awl. Heavy duty Leatherman-quality tool in a compact size. I've had mine for about 3 years and put it through a lot of abuse and it's still in great shape (except for the finish that got banged up when I tried to use it as a hammer once--just go get a hammer if you need one, this tool isn't a very good hammer).
Serious mom usefulness for cutting the dumb little ties that hold price tags on, filing the rough spot off your kids' coat zipper so they'll zip their coat up all the way, cutting boxes open and slicing apples in the car, unscrewing battery compartments, and untying the bouquet of balloons that the kids just asked you to tie together (no, I didn't just cut all the balloons with the knife like I wanted to do, I actually used the pliers to untie them).
The blade could stand to be a little bigger (it's only 1 1/2 inches long), but then it would be a regular leatherman and you'd have to carry it in a sheath on your belt which belt I do not wear or in your purse which is already heavy enough and if you're like me it gets forgotten at the house far too often. This little baby goes in your POCKET so it rarely isn't with me. And it comes in Gray, blue, red, or pink. I could seriously be a leatherman salesgirl just for this tool. :)
They have a scissor version (the Squirt S4) and an electrical version (the Squirt E4) with wire strippers, but I wouldn't give up my pliers for scissors especially when the pliers have the wirecutters which cut most things I need to cut and I'd rarely use wire strippers either. So you see, it is an amazingly useful little tool every mom needs. And I suppose it would still be useful if you're not a mom, I just call it my mom tool because it so often is used in my mom duties. Yep, you need one. ;)