If you are trying to achieve something like this:
http://gregaitkenheadphotography.com/
Photographer Greg Aitkenhead discusses using the plug in “Ultimate Category Excluder” to do it.
His articles “Zen Minimatica” (http://gregaitkenheadphotography.com/zen-minimatica/)
and
Unofficial Minimatica Users Guide (http://photohow2.com/2011/10/minimatica-user-guide-how-to-set-up-a-wordpress-photography-portfolio/)
give a lot of detail.
Hope this helps.
Cheers!