A smartphone is really just a computer. It’s smaller, of course, and many things are less convenient than a regular desktop. But smartphones have powerful features, and once you’ve upgraded to a better model, you may wonder what to do with all that valuable hardware.

Even without their cell signal, smartphones may still function just as well with a Wi-Fi connection, making them (essentially) miniature tablets. You can use all those apps and features you always had, and you can access the internet and even use regular communications like iMessage, Skype, and WhatsApp.

Related: Here are 7 surprising things you can do with your smartphone’s camera you never knew before now.

Yes, you can rid yourself of an old phone, and there are many prudent ways to do this. You can sell it or trade it in. You can also repurpose your gadget for work, lifestyle, or entertainment. In short, don’t let that thing waste away in a drawer. Put it to good use – even if it’s somebody else who’s using it.

Here are 9 nifty things you can do with an old cell phone.

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1. High-tech alarm and sleep tracker

Most cell phones come with a built-in alarm. Even if you're not paying for cell service on your old gadget, you can still use it for certain apps that you've already downloaded. You can also download a white noise app to help you sleep. Click here to try an app called Relax Melodies.

Better yet, use that old phone to track your sleep. As a sleep tracker, the app Sleep Cycle will let you know not only when you fell asleep, but also how well you actually slept. The data is presented in an easy-to-understand graph, which will be accompanied by details as well as ideas to help you sleep better in the future. Click here for this great app to monitor your sleep.

2. Convenient eReader

Kindles and Nooks were originally designed as eReaders, but many apps will enable you to download and read an ebook right on your phone. The most popular eReaders are the iBooks and Kindle apps, but you can find others as well.

Granted, smartphones have smaller screens than your standard eReader, and they’re backlit, while the average Kindle screen behaves more like printed paper.

For many of us, that’s a small price to pay to carry an entire library of books in our pockets. The old phone can also make a great backup when you’re traveling light. Click here to learn about the Kindle app.

3. Entertainment center

Smartphone storage has grown exponentially in recent years; the latest iPhone models have up to 256GB. That amounts to thousands of songs, movies, podcasts, and games. This is an excellent alternative to your regular phone, since you won’t receive calls and your mp3s don’t have to compete with more critical data.

Now that you can download and watch movies from iTunes, Amazon, and Netflix, you could watch half a TV series on a single flight.

4. Children’s camera

The best smartphones have cameras with roughly the same resolution and optics as a regular point-and-shoot, and some photographers prefer an iPhone or Galaxy, because photos can be edited and shared. You may have retired your phone, but the camera is as useful as ever, which makes it the perfect learning tool for children.

Before you hand over an expensive point-and-shoot or new smartphone, let your kids practice taking photographs with that old device.

5. VR headset

You’ve probably seen commercials where people strap a phone in front of their eyes and have a blast playing games and experiencing new worlds through virtual reality. It can be a lot of fun, but it also requires moving your phone in and out of a VR headset mount. Your old iPhone can become your full-time VR gadget.

You will need to pick up VR goggles that are compatible with your model of iPhone. Check out the Google Cardboard goggles as an inexpensive way to get started. From there, you can try out a variety of VR apps available through Apple’s App Store. The Google Cardboard app works with the Google goggles and is a good place to start your VR journey.

6. Control your Apple TV

The Apple TV remote is a model of minimalist design, but this means it can be a little cumbersome to use. Make your life easier and download the Apple TV Remote app to your old iPhone. Now you can navigate the Apple TV interface, conduct searches, and control your streaming entertainment with ease.

If your remote-control ambitions extend beyond just your Apple TV, check out the Pronto Smart Universal Remote Control for iOS. This device works in combination with the Peel Smart Remote app to turn your iPhone into a universal remote control that can handle almost any television, stereo system, or another home-entertainment device.

Your iPhone doesn’t contain an IR blaster (the infrared technology used by most remote-control systems), but the Pronto and Peel combination makes up for this shortcoming.

7. Set-up home security

With increasing popularity, many users are turning old phones and tablets into a home security system.

With their Wi-Fi and high-res, built-in cameras, an old smartphone (or tablet) can keep an eye on your home at all times. You can download the Skype app and set it up to automatically accept incoming video calls so you can check on things while you're out. Click here to download the app.

For more sophisticated surveillance, you can find specific home security apps. Presence is a popular option, but you can also check out Manything and Alfred. Install the app, set it up, and place your phone in a strategic spot. These apps offer live video streaming and motion-detection alerts. You can keep an eye on your front door, use it as a nanny cam, or check in on your pets when you’re traveling.

On a related note, your old iPhone can act as a video baby monitor through the use of the $4 Cloud Baby Monitor app, which can send noise and motion alerts to your current phone and let you look in on your young one.

8. Donate it One other way to handle your no-longer-needed cellphone is to donate it to a good cause. Cell Phones for Soldiers accepts both smartphones and tablets. You can either ship them in or find a local drop-off location. The amazing nonprofit provides free talk time to soldiers and assists with emergency funding for both active-duty personnel and veterans.

9. Use it for emergencies

Even if you don't have an active mobile plan on an old phone you can still use it to call emergency services. By law, all cell phones are required to allow you to call 911, even without a service plan.

Just make sure the device is always charged and you'll have it on hand whenever an emergency arises. Place the phone in a convenient location, like your purse or glove compartment.

What questions do you have? Call my national radio show and click here to find it on your local radio station. You can listen to the Kim Komando Show on your phone, tablet or computer. From buying advice to digital life issues, click here for my free podcasts.

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Learn about all the latest technology on the Kim Komando Show, the nation's largest weekend radio talk show. Kim takes calls and dispenses advice on today's digital lifestyle, from smartphones and tablets to online privacy and data hacks. For her daily tips, free newsletters and more, visit her website at Komando.com.