You could use Find. When looking at a Contact Sheet:
1: Command-F
2: Click Set Check Boxes on None, then check Keywords
3: Type in a keyword
4: Click "Find"
All the images tagged with that keyword will be highlighted. You can quickly then invert your selection to highlight only the images NOT tagged with that word with Shift-Command-o
You can also have the contact sheet show the keywords for each image, but if there are many keywords, you will not be able to see them all. To do that:
1. Go to Preferences (Command-,)
2. Go to Contact Sheet
3. In the section Labels, you can add another label and make it {keywords}
Maybe one of these two ways can help.
-Mick
