I played a bit with combining Chandra, Hubble, and Spitzer images together. I used the raw data available on the websites to rework the images so that the filters in the respective bands are ordered (R-->B : long wavelength --> short wavelength). This is a different palette than was used for many of the released images.
As described in the tutorial, I used a Hue/Saturation layer to colorize the grayscale images and then used "Screen" blending mode rather than loading into the RGB channels. That gave an interesting effect that might be useful for adding bonus channels in planetary images....
Links to images on my flickr site:
Cassiopeia A supernova remnant (Spitzer/Hubble/Chandra): http://www.flickr.com/photos/31678681@N07/4842001649/
E0102 supernova remnant in the Small Magellenic Cloud (Spitzer/Hubble/ + Halpha (orange) + [OIII] (blue-green)): http://www.flickr.com/photos/31678681@N07/4839139715/