Update: Take a pass on this one for now, our commenters and others are saying the software isn’t ready for prime time yet.
iDisplay is a $5 app/ Mac Application that will turns your iPad into a second (or third) display. It doesn’t mention anything about being able to use the iPad as a Wacom tablet like the Mimo does, however. Still, for $5, it is nice to have an additional display. Oh and it also works on iPod touches and iPhones.