Mac only. So, you own both a Mac and iPad? Do you know that you can turn your iPad into a wireless secondary display for your Mac?
iDisplay (USD $5) is an iPhone/iPad app to extend your Mac display to your iPhone, iPod Touch, or iPad. You can use the extra display for your Twitter, instant messaging, weather, news widget, etc.
Brilliant idea! Another reason to buy Apple iPad, uh?
To get iDisplay work on your Mac, beside purchase iDisplay app, you also need to install the iDisplay desktop.
Does it work well? Not really.
Anyway, we could expect the iDisplay developer, SHAPE Services to fix and refine iDisplay very soon.
SHAPE Services is also the developer of IM+, the popular instant messaging app for iPhone.
Update: iDisplay for Windows is under development.