If you're like most Americans, you're probably holding on to your old gadgets for far too long: According to a recent survey from uSell.com, 42% of Americans suffer from "Extreme Gadget Obesity," keeping their older, unused gadgets for at least two years.

If you're among that 42%, you're probably making a mistake.There are all sorts of businesses willing to buy gently used electronics, often for a quick cash payment or a gift card.

Simple trade-in programs
If you want to get rid of your stuff quickly, and you're not willing or able to invest a lot of time or effort, consider taking advantage of the growing number of websites that specialize in used gadget trade-ins.

Gazelle is perhaps the most popular, but it has several competitors, including Next Worth, uSell, and BuyBack World. Policies vary, but in general, the process is fairly straight forward: You list your device and its current condition; they provide you with an offer of what they're willing to pay; and if you accept it, ship them the device and get paid.

Unfortunately, the prices they offer can be quite low -- the cost of convenience -- and the gadgets they accept are limited. For the most part, they all buy smartphones and tablets, but nothing else is guaranteed. Gazelle will take Apple Macs and iPods; uSell accepts textbooks and game consoles; Next World will pay for some Windows PCs and e-readers.

If you're stuck with a device one of those websites does not accept, there is always the Amazon (NASDAQ:AMZN) trade-in program. The e-commerce giant accepts literally thousands of different electronics and provides free shipping to boot. Unfortunately, Amazon only pays with gift cards, but at least it is another option to consider.

Online marketplaces
If you're willing to put in a little time and effort, you may want to look at one of the various online marketplaces.

You can sell basically anything on eBay (NASDAQ:EBAY) -- no matter its condition or its age. Millions of customers visit its website regularly, and the best chances of finding a buyer for your cracked iPhone 3GS are here. There are other, more specialized marketplaces, such as Swappa and Glyde, that provide a better experience, but sellers are restricted in what they can offer.

Amazon has an individual seller program that allows anyone to list used items on its marketplace, in a manner remarkably similar to eBay. If you opt to use its Fulfilled by Amazon program, it will even store the devices for you in its warehouse, ship them when they're sold, and take care of the customer service. However, Fulfilled by Amazon carries a number of fees -- most notably, Amazon charges monthly storage fees on unsold inventory -- which may make it unsuitable to those just trying to clean out their closets.

With the exception of that particular program, marketplace selling can be quite a hassle -- you have to write descriptions for the items, take appropriate pictures, answer customer inquiries, and handle both shipping and returns. But if you're willing to do all that, you can maximize the amount of money you'll get for your devices.

Bricks and mortar options
Finally, if you prefer to do business in-person without the need to wait or ship anything, there are several stores that accept trade-ins on a local basis.

GameStop is famous for its video game trade-in program but has recently expanded into other electronics. Bring an Apple TV or iPad into your local GameStop, and you can walk out that day with cold, hard cash. Wal-Mart, Best Buy, and Target all have similar programs, but they also pay with gift cards. Given the diversity of their offerings, however, that might not be much of an issue. Both Apple and Microsoft retail stores also accept trade-ins.

Outerwall -- the parent company of CoinStar -- has expanded into this market recently with ecoATM.  It is still a relatively new venture, with a limited rollout, but if you happen to live near a machine, you can sell your gadgets at any time of the day without needing to interact with a clerk.

Don't be a gadget hoarder
With so many different options, there is simply no reason to hold on to your old, unused devices. If you're not using them, you no longer have any excuse not to turn them into cash.

Sam Mattera is short shares of GameStop. The Motley Fool recommends Amazon.com, Apple, and eBay. The Motley Fool owns shares of Amazon.com, Apple, eBay, GameStop, and Microsoft. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.