This is the 6 string version of Virtual Guitar. Download
It can show you all the modes based off of the Major Scale at the click of a mouse and many other common guitar scales.
Here is a list of some of the scales for the Virtual Guitar:
Major and Minor Pentatonics
You can hear what multiple notes sound like by clicking and dragging on notes you want to hear. This is good for hearing what a chord sounds like or for interval training.