I have three kids. My wife, mother and I all have iPhones. This is not a coincidence. It didn’t take long after the introduction of the iPhone to realize that the iPhone was a great tool for entertaining youngsters and buying parents some peace… provided said youngsters are not fighting over the device itself. If you’ve got children and an iPhone in the same house, kid-friendly applications are a must-have. Here are my favorites — all links are iTunes links.

For younger kids, Bubbles and BubbleWrap are both free and wonderfully simple. Bubbles lets you conjure bubbles with a sweep of your finger, which you can then pop with a tap or just watch drift away.  BubbleWrap lets you pop virtual bubble wrap, racing to see how many bubbles you can pop in 45 seconds. Unlike the real thing, this bubble wrap never runs out of bubbles.

Even simpler is Moo. It moos. Free, and good for a few giggles, so definitely worth the price.

If your kids like to ham it up, they’d probably love CrazyMouth (Lite), which basically puts a big cartoon mouth on the screen that your kids can then hold up to their faces, letting them express the toon within. There’s also a paid version with more animated mouths, and another variation called CrazyEye.  Personally, the free version was more than enough.

For young kids with an artistic streak, there’s Scribble, a simple painting app. A palette of colors and pen sizes lets you draw shapes (on a blank canvas or on a photo) or practice writing.  You can save the artwork to your photo album (where you can e-mail it to appreciative grandparents), or erase it with a quick shake.  There are lots of other drawing apps, but I keep coming back to Scribble for its simplicity and price: free.

If your kids are older — say, four to six years old — they might want more of a challenge.  There’s Match by Jirbo Kids, a basic memory game that the company says is “free for just a few more days.”  Not complex enough? Ease them into arcade games with Chimps Ahoy! Lite, a fun game sampler that’s worth the download merely for its “Breakout”-like experience.  It’s free, but if you fall in love with the chimps, the full version offers 100 levels for just $2.99.

Finally there’s Tap Tap Revenge, the free, finger-sized version of “Dance Dance Revolution.” Grown ups like this one as much as the kids.  A warning, though: the songs get stuck in your head. Especially if your kids, like most kids, play everything over and over and over and over again.

Like many of the best iPhone applications out there, it bears repeating that all of the apps I’ve mentioned are free.  If you’re willing to spend a little money, though, a few honorable mentions: Preschool Adventure costs a buck, but could easily replace a backpack full of activities for little ones. I could see paying much more for this colorful, elegant application. And for older kids, there’s Cro Mag Rally, a fun racing game that used to cost $10 but is temporarily discounted to $2, and top seller Super Monkey Ball, which is a top seller for a reason.  When it comes to making use of the iPhone’s accelerometer (and involving a whole different dimension hand-eye coordination), it’s fun to play… even if your monkey plummets off the edge every single time.

So go ahead and take the time to set up a kids-only page of apps on your iPhone.  You may have second thoughts about letting kids play with an expensive gadget. I say they’re going to get their little paws on it sooner or later. You might as well have something waiting for them… lest they decide to start deleting contacts instead!

Note: These applications also work on the iPod Touch, and hopefully any future Apple hardware designed to work with Apple’s App Store!