The cpt-city website has a large collection of over 4,000 color tables (download of over 4,000 color tables). Unfortunately for us (i.e., me), they are all in the .cpt format used in GMT. Here’s a routine to read a .cpt file and return it as a 256 by 3 color table array:

IDL> rgb = vis_cpt2ct('gmt/GMT_copper.cpt')
IDL> help, rgb
RGB             BYTE      = Array[256, 3]        
IDL> tvlct, rgb

Now I need a catalog that I can scan through to find a color table.