Provide actual NDVI values with image

[frankvideots]

Provide an average NDVI value around a selected area(s) and/or just under the pointer.

[mathewlippincott]

or maybe just a standard chart showing what the different colors mean. no way to know when looking at current infragram pictures.

[btbonval]

usually there's a colorbar for things like that. See the examples in Matlab:
http://www.mathworks.com/help/matlab/ref/colorbar.html