iDisplay is exactly the type of app I’ve been waiting for since the initial release of the iPhone. It’s an app that turns your iDevice into a mini monitor suitable for small apps like Twitter, buddy lists or tool palettes. It’s a perfect idea, but less than desirable in terms of performance. iDisplay will need to see some significant improvements before I’d recommend it to anyone.

The DoubleSight USB monitor is one of the many options available today in the world of USB displays. DoubleSight has 7 and 9 inch models, and you can even get a webcam to go along with the 9 inch model. The 9 inch also obviously benefits from a higher display, but both are about the size of an average netbook screen (if that’s something you’re familiar with). I tested out the DS-70U, the 7 inch model. The display powers itself and connects to your Mac (or PC) using two USB connections.