Unfortunately, it’s also a bit on the spendy side. While $10 really isn’t that much to spend for quality software that lets your Mac use an iPad as a second monitor, some folks might not want to spend that much without giving it a good try first.
Lucky for this group of folks, developer Avatron has recently released Air Display Free, an iOS app that lets you use your iPad, iPhone, or iPod touch as a second monitor for your Mac. It’s free to download and use, and is supported by advertising so that budget-conscious folks can try it out without having to spend a dime.
There’s a nice little intro tutorial on using Air Display as an external monitor, and the ads are fairly unobtrusive, though they will stay on the screen after a few hours of use. You’ll be able to upgrade to the paid version to get rid of the ads, of course, which is the idea behind an ad-supported app like this.
You’ll need an Intel-based Mac running 10.6 or later to run this and the non-free version of Air Display.