Turn your iPad into a second monitor for $9.99

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Look at that iPad of yours, just sitting there doing nothing while you slave away at your laptop. What a slacker!

Okay, it's not like you can really use an iPad while you're working, right? Wrong! Turns out you can use it as a second monitor. All you need is the right software.

And here it is: For a limited time, you can get Duet Display for iPad for $9.99. Regular price: $19.99. That may still seem steep for an app, but consider what it would cost you to add an actual second monitor -- and how few "real" monitors can fit in your carry-on.

This isn't the first or only iPad-as-second-screen solution, but it's definitely one of the best. (Indeed, Lifehacker named it the absolute best last year.) That's because it leverages a wired connection, thereby minimizing the often-severe lag inherent in Wi-Fi screen-sharing. Yes, it means looking at a USB cable snaking around your desk, but trust me when I say it's worth it.

All you do is install Duet Display on your iPad, then install its desktop counterpart (available for Windows and Mac, no additional charge). Run them both, plug in a USB cable, and presto: second screen. The app supports 30- and 60-fps modes, portrait and landscape, Retina displays and both mirror and desktop-extension modes. (It sets up the latter by default.)

In my tests with an iPad Air, it worked exactly as advertised, though it took some fiddling to find an iPad resolution I liked. Too low, things look grainy. Too high, things look too small. But there was virtually zero lag, especially at the lower resolutions.

I'm a big believer in dual monitors. When you're able to keep, say, your browser and word processor open side-by-side, it's really powerful. Or your browser and email client. Or a spreadsheet and sales report. You get the idea.

If you own an iPad Pro 12.9, this is a great way to wring some extra value from your purchase. But even a 9.7-inch iPad can prove useful as a second monitor. And now it'll cost you only $10 to make it happen.

Your thoughts?

Bonus deal: Speaking of screens, if you're in the market for something a little bigger and more traditional, look no further than this stupid-good deal: Today only, and while supplies last, Best Buy has an AOC 24-inch LED desktop monitor for $79.99. Two-day shipping is free; sales tax, not so much. The monitor features HDMI and VGA inputs and comes with a three-year warranty. Plus, it's really skinny, not one of the chunkers you typically see in the monitor-bargain basement.

Bonus deal No. 2: And now for something completely different. Today only, and while supplies last, Woot has the refurbished Samsung NC240 23.6-inch LCD monitor for $79.99, plus $5 for shipping. Why would you choose this over the AOC? Because it's actually a zero client, meaning it's designed to connect to a remote PC. You need some technical (read: virtual machine) know-how to leverage this, but I just thought it was an interesting deal: The NC240 sold for $815 when it was introduced back in 2010. And, elsewhere, refurbs sell for around $300. Read this FAQ before you even consider buying, though.

Bonus deal No. 3: If you're going to buy a sound bar (and you should, because your TV's built-in speakers are awful), get one with a subwoofer. And if you're going to buy a sound bar with a subwoofer, make sure it supports Bluetooth so it can double as a Bluetooth speaker. For a limited time, and while supplies last, Woot has the refurbished LG LAS350B 2.1-channel sound bar with Bluetooth for $64.99, plus $5 for shipping. It lists for $149, and the best price I've seen elsewhere for a refurb is $84.

I haven't found any pro reviews of the LG, but if you check the Google reviews, you'll see an impressive 4.5-star rating from over 160 buyers. And the ratings are similarly enthusiastic at stores like Tesco and Walmart. Woot backs the product with its own 90-day warranty.