I’ve written about V-Control before, it’s a virtual control surface for various DAW applications including Pro Tools, Logic and Cubase. Version 1.5 has added a great new feature called V-Window that allows you to directly control any window (plugin, floating panel, edit etc) directly on your iPad.
If you have an iPad and are looking for a control surface then at $50 this is a steal. You get a transport control. direct access to mixing controls including a surround panner and now plugin control on a wifi connected device. The control response is instantaneous but be aware that screen redraws on the ipad particularly with V-Window lag behind as with any VNC like device.