Turns out, a stud is more than just an embellishment that makes your clothes look edgy or a hot guy. It's also a piece of metal or wood supporting your walls that you can use to hang things even if the wall material itself is too flimsy.
This handy gadget uses a magnet to help you detect them. It also has a built-in level you can use for hanging once you've found the stud.
Promising review: "This is a GAME CHANGER! Every once in a while, a new device renders all the old ones utterly obsolete. So it is with these stud finders. Oh, yes, I’ve used the old battery powered devices — I own several. You know, the ones with little LEDs that supposedly light-up when you’re over a stud—except that they keep lighting up in different places so that you ultimately give up and just drive in a nail into the wall and hope you’ll be over a stud. No more! Gently rub these little gadgets over your wall, and when there’s a nail underneath the sheetrock, its powerful magnets will be drawn to it, and IT WILL STICK TO THE WALL! There is NO guessing with this little fellow." —Moi Aussie
Also, bear in mind that if the magnet is sticking to a larger stretch of wall, not just one area where a nail would be, you may have found a pipe, so don't drill there!
Get a set of two from Amazon for $19.06.