Upgrading to a new smartphone or tablet always feels like Christmas morning, but it also leaves you with an old gadget that’s taking up space. Usually, nothing is wrong with it. You just don't need it anymore.

Or do you? Before you decide to sell it or give it away, there are some very cool things you can do with it. You'll definitely want to give these a try.

1. Security camera

You don't need a complete security system to watch a single room, closet, drawer or jewelry box. A single Internet-connected security camera can do the job, but why spend the money?

With a simple free app, you can transform your Android or Apple gadget into a motion-activated security camera that records images and alerts you when someone comes snooping. Check out Salient Eye (Android; Free) or Manything (Apple; Free). Then click here to learn how to make them work and what to do if you need more security in your home.

2. Digital photo frame

If you want to frame a digital picture to hang on the wall, you have to print it out. Of course, thanks to easy digital photography, you probably have hundreds or thousands of great pictures to choose from.

Instead of trying to choose, turn an old tablet into a digital picture frame. It can sit on a table or counter and display hundreds of great photos in sequence.

For an Android tablet, grab the Dayframe app (Free). Not only does it let you set up photo slideshows from local photos, it can pull images from Facebook, Instagram, Twitter and other major photo and social media sites. Plus, if you have a Google Chromecast, you can easily stream photos to your TV and turn it into a giant digital photo frame.

For an iPad, Digital Photo Frame (Free) and Picmatic (Free) are two good apps. Digital Photo Frame lets you pull images from online sources, while Picmatic lets you add filters and create interesting layouts.

3. Universal controller

Tired of juggling remotes for your TV, streaming box, Blu-ray player and more? You can turn your old gadget into a universal remote control for your entire home entertainment system.

Most new Internet-connected TVs, Blu-ray players and streaming video boxes have remote apps. Simply load the app on your gadget and you have complete control over Wi-Fi. For older gadgets, you can get an IR transmitter adapter like the Zmart Remote PRO or a Wireless-to-IR base station like the Logitech Harmony Hub.

If you have other Wi-Fi enabled appliances in the house, like smart light bulbs or thermostats, you can control those as well. And you don't have to stop at your entertainment system and appliances. An app like Remote Mouse (Android, Apple; Free) lets you control your computer using your smartphone or tablet over your network.

4. For the kids

If your children are clamoring for a gadget of their own, an old one is perfect for watching videos, reading eBooks and playing games. You can set it up so they stay safe. And if they destroy it, it isn't a real loss.

On Android tablets with version 4.3 and up, you can create Restricted Profiles under Settings>>Devices>>Users so you have complete control over what your kids are doing. Apple lets you enable restrictions on in-app purchases and some apps.

You can also install a third-party app like Famigo (Android, Apple; Free) that locks the gadget into a kid-friendly mode. Click here to learn more about sharing tablets with people and still keeping your privacy.

You'll also want to install an app like DinnerTime (Android, Apple; Free) that lets you shut down the gadget when the kids start misbehaving or it's time for family dinner.

5. eBook reader

A good use for an old tablet is a dedicated eBook reader. You can install the Kindle app (Android, Apple; Free) to read any of your Amazon eBooks, or buy new ones from Google Play or iBooks. 

You can also rent eBooks from your local library through the Overdrive app (Android, Apple; Free). Or download free ones online from Project Gutenberg or other online eBook collections.

6. Alarm clock

I know a lot of people use their smartphones as their alarm clock. While this gives you more alarm options than your typical clock radio, it can disturb your rest if you get texts or notifications during the night.

Using an old smartphone or tablet means you can turn off any distractions and just use the gadget as an alarm clock. Apple and Android both have good built-in alarm functions, but you can do more.

Grab an app like Sleep Cycle Alarm (Apple; $1), Sleep As Android (Android; Free) or Sleepbot (Android, Apple; Free). These track your sleeping patterns and wake you up at exactly the right moment so you're refreshed.

7. Dedicated car player

Tired of getting in the car and spending a minute or two plugging in your phone so you can listen to your music? Load your music library on your old phone and stick it in your car permanently. Click here to learn how you can turn an ordinary binder clip into a smartphone holder for your car.

Turn on the Wi-Fi so it connects to your network while the car is parked at home to grab new music or your favorite podcasts. You can also grab an app like MAPS.ME (Android, Apple; Free) that gives you navigation without a cellular connection.

Bonus tip: If you are going to sell your gadget, or give it away, make sure you wipe your personal information off of it completely. Click here for step-by-step instructions to keep snoops from getting their hands on your information.

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. Kim also posts breaking tech news 24/7 at News.Komando.com.