I would like to have a different image for the thumbnail than the what the customer sees when he clicks on it.
For example: In my color attribute I want to upload color samples and a preview of that product in that color. I'm sure this is possible somehow but I can't seem to find the proper module or feature. If I have to I will create the module myself but it seems like it should be something that would be in high demand so I can't figure out why I can't find something.
Start with the Imagecache module (http://drupal.org/project/imagecache), you can create a preset that will derive an image from another image field. You could then write your own image cache plugin that could generate a preview for a specified color.
I haven't played with Ubercart so I'm not sure if there are limitations of which I'm not aware, but you should be able to create 2 imagefields in your content type. One called something like "teaser image" and one called perhaps "product image". Set up whatever imagecache presets you need and configure your content type to display "teaser image" in the teaser but hide "product image" and vice-versa for the full node view.