Can I use an iPad as the display for a Mac Mini?
Solution 1:
You should be able to set up the VNC server on the Mac (it's under System Preferences > Sharing > Screen Sharing), and use a VNC client on the iPad.
This goes over the network, not through a cable. It's possible there's an app and cable solution, but I haven't heard of one.
I just found this post, which describes how to set up the Mini side of it.