Check out the no bake granola bar recipe I posted on August 27, 2008. I have since re-vamped it, which has greatly improved how it holds together. If you had trouble with your bars crumbling, try making them with the new method.
Basically I melted half the chocolate chips with the other things I melted, AND I now add more of the "melting" items than I used too. This really helps everything bond better. You can find this recipe by clicking on "oats" in the LABELS section to the right or by clicking here!
I also throw all the melty stuff in a big Pyrex measuring bowl & mix it up. Then I microwave it for about 3 minutes... till it's hot and bubbly.