The iPad is loaded with all kinds of features you've probably heard about, but look a little deeper, and its extra abilities might surprise you. Some of these secrets are enabled through apps, while some are built into the device already.
Turn Your iPad into a Secondary Desktop Display
With its big, high-resolution display, it's a shame to just park an iPad when switching to a computer. Instead, Air Display (US$10) makes your iPad a second screen for your Mac, extending the desktop. The tool has just been submitted to the App Store and should be released soon; I checked out a beta.
You install a utility on the computer and connect with the Air Display System Preference. (It's Mac-only at launch, but a Windows version is coming.) The iPad then behaves just like an extra screen. You reposition it in the Displays System Preference like a real monitor, in a portrait or landscape view. Although it lags a little when showing video, it refreshes quickly enough for most work. You can even tap on the iPad to click.
If you can't wait for Air Display's release, you can check out iDisplay ($5) now. But this buggy competitor needs an update to match Air Display's ease.
Stream Movies From Your PC
Even if you bought the largest-capacity iPad, if it can't fit all of your videos, it's too small. Instead of trying to cram everything into the device, you can stream videos from a local or online PC. The process has one main caveat; if you bought movies or TV shows from the iTunes store, DRM restrictions block those files. (Podcasts and music videos should work.). But you can watch your own videos or DRM-free downloads without taking up iPad storage.
Of the many options available, I like Air Video ($3) the best. (A free version includes the same functions but limits the number of files you can browse in each folder). Similar to competitors, you run a server utility on your PC or Mac in order to route data to the iPad. In my tests, Air Video played most resolutions smoothly, including 720p video files over an 802.11n Wi-Fi network.
That resolution stutters on an 802.11g network, but if you reach a file that's too big--or just not in an iPad-friendly QuickTime format, including AVI, WMV, ASF, MKV, DIVX, and FLV--you can have the PC remotely convert the clip. Just hit a button from the iPad interface and stream it when ready, or have a speedy PC process it and stream it live. It even supports subtitles and TV output. The iPad can send video to a TV at 1024 by 768 resolution via its $29 Dock Connector to VGA adapter; 576p and 480p with the $49 Apple Component A/V Cable, and 576i or 480i with an Apple Composite Cable (also $49).
Connect More Than a Camera
Apple's iPad Camera Connection Kit ($29) does so much more than its stated purpose. Instead of just transferring photos and videos from your camera or SD card, the adapter's USB port attaches a range of devices.
Many USB keyboards work. The iPad presents a warning that the device isn't supported (shown left), but if it doesn't draw much power, you can ignore the message. Volume and media keys usually work, and you can even use desktop commands such as Command-Z. (Don't forget that the iPad also officially supports Bluetooth keyboards and Apple's iPad Keyboard Dock).
USB audio devices can work, too--including speakers, headsets, and microphones. If a device draws too much power and balks (as when I connected a Zoom H2 mic and Logitech V20 PC speakers), no problem: just attach the device to a powered USB hub, and connect the hub to the Camera Connection Kit adapter. You can even attach different devices--such as a keyboard and speaker set--at the same time.