Story highlights You can sell old computers, tablets and phones online for cash

Many manufactures and online retailers buy back old devices for credit

Donate computers and tablets to schools, or phones to a number of charities

If something can't be sold or donated, don't throw it out; recycle it for free at Best Buy

If you received shiny new gadgets for the holidays, you probably have some older device that is now unwanted or obsolete. If you can't regift your old computer, tablet or TV, make sure you get rid of it the smart way by selling, donating or recycling it.

Before you part ways with your device, make sure to wipe it clean and permanently delete any personal data.

Sell for cash

If you'd like cash in exchange for your gently used gadgets, you can sell them online. How much money you earn depends largely on how much time and effort you're willing to put into hawking the device. It's easy to get caught up trying to get the best possible price for your old iPad or smartphone, and before you know it you've wasted a chunk of your holiday vacation jockeying for an extra $50.

Selling directly on sites such as Craigslist eBay or Amazon can net the best prices, but it also comes with its own set of hassles, including the time commitment required to sign up and create a listing, as well dealing with flaky buyers.

Technology depreciates quickly, so you're unlikely to make back the full $500 you spent on an iPad 2 just last year. To find out how much you can get, look at past eBay auctions for the same item. Do a search for the gadget name and select "Completed Listings" from the Show Only menu, then select the auction tab at the top of the list. Prices will vary according to condition. For example, an unopened Nexus 7 in the box recently went for $251, while a Nexus 7 with a cracked screen sold for just $81.

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You can also check Pricenomics.com to see a list of current sales and a handy chart showing the average price of the device over time.

For an easier but less lucrative selling experience, consider using one of the many sites that specialize in buying used electronics. Gazelle.com buys back Apple products and some third party smartphones. NextWorth buys back iPhones and iPads, as well as cameras, e-readers, game consoles and other products. It will pay around $74 for a Nexus 7 in good condition. If you have an old cell phone, try ReCelluar

Buy back kiosks are popping up across the U.S. EcoATM examines your device and offers a price based on its condition. If you decide to sell it, you'll drop in you device and receive cash right away. You can search for the nearest EcoATM on the company's website

Trade for credit

If you're going to use any profits to buy even more technology, trade-ins can offer a better deal than selling. Most major electronic retailers have established trade-in programs that offer store credit toward a future purchase.

First check with the manufacturer of your device to see what kinds of prices they're offering. Apple has a Reuse and Recycling program that offers Apple Store credit for your old iPads, iPhones, iPods and computers. Wireless carriers including AT&T T-Mobile and Verizon buy back old phones for store credit.

Amazon's trade-in site will buy back Kindles as well a variety of other electronics. It even takes video games, music and movies. In exchange, you're issued an Amazon.com gift card that you can use for any product on Amazon.

Donate for karma

You might not do much with the hundred or so dollars you get for that used laptop, but a local school or library could benefit greatly from having more working computers. There are many options for donating your old devices, from local charities to larger established programs.

Goodwill and Dell teamed up for the Reconnect program, which accepts donated computers at select Goodwill locations. The official site has a full list of items it will accept and locations near you. The Salvation Army also accepts used computers and electronics.

You can also call local schools or community centers directly to see if they accept donations. AmericanCellPhoneDrive.org will find nearby organizations accepting phone donations.

Recycle for the environment

If your device is too old or damaged to sell, don't just chuck it into the trash can, recycle it. Most governments offer local options for electronics recycling. Check in your area for schedules and drop off locations. Recycling keeps dangerous chemicals out of landfills and saves natural resources by cutting down on mining and minimizing pollution resulting from manufacturing. (Recycle any batteries separately.)

Many electronics manufacturers also have mail-in and drop-off recycling programs for their old devices, including Apple, Samsung and Sony. Wireless carriers will take old flip phones at no cost.