Windows/Mac + iPad/iPhone: Back in February we highlighted Air Video, an incredibly cool app that streams any video from your computer to your iPhone, no matter the format. Now it's updated with an iPad version, and it's incredible.
(Click the image above for a closer look.)
The concept behind Air Video is pretty simple: Your iPad/iPhone can't play all that many video formats, but you've got countless types of videos on your desktop. You don't want to convert them all just for your stupid iPad, but even if you did, you'd be eating up your precious iPad hard drive with video, and you don't want to do that.
If you're willing to shell out $3 for Air Video (you only have to pay for it once, so if you buy it on your iPad, you also get it on your iPhone, and vice versa; a free version is available, but the $3 version is worth the cost) and then download and install the free server software (available for both Windows and Mac), Air Video will convert and stream any video on the fly, directly from your computer to your device, no matter where you are.
Whitson explained the setup when he first covered Air Video, but for a refresher, once you've downloaded and installed the server and the iPad/iPhone app, all you've got to do is enter a unique PIN in your device. To get the PIN, just open the server settings on your desktop and navigate to the Remote tab. I'd recommend sending yourself an email with the PIN in case you're ever with a friend and want to give them access to your library.) Then open the app on your device, click the '+' button to enter your PIN, and you'll be streaming videos before you know it.
You'll want to add all your pertinent movie/tv/video folders from your desktop. Just find the Shared Folders tab and start adding anything you want. Once added, those folders will instantly become available on your device.
The main selling point for Air Video: It works really, really well, and there's nothing to setting it up. If the iPad truly is a consumption device rather than a creative one (I might argue with you at least a bit on that point, since my primary activity on this thing has actually been drawing with Brushes), then Air Video makes it an order of magnitude better at consuming video. The streaming quality is really impressive, whether or not you're streaming over your LAN (obviously local streams yield higher quality).
In fact, even if you were only using it to stream video over your local network, it's still better than bogging your device with giant video you'll just have to remove to swap in other ones. (Be sure to check out Joel Johnson's great review of Air Video for iPhone for more specifics; he tested it against a lot of popular codecs and had all kinds of good feedback.)