I think chromatic exercises are good for many reasons. First off... great warm up exercises come from chromatic exercises. Secondly, there really good to know for when your in a pinch. Sometimes very organic sounds are found this way.

Check out this site:
http://www.guitarsite.com/PickingExercises/chromatic1.html

Check out my page...
http://groups.msn.com/GuitarPage/homepage.msnw