Demonstrating Impact, Value and ROI
See my Dialog Quantum case study "Return on Investment" here http://quantum.dialog.com/q2_resources/casestudies/roi.pdf
In late 2001 the BNA Library conducted this ROI study to measure our impact on BNA's bottomline, and our research showed that for every $1.00 spent on the Library, we returned $1.26.
We will be updating the study this summer (2006) and I expect to post the update to the Quantum website in Fall 2006.
Marilyn Bromley Library Director BNA, Inc. firstname.lastname@example.org
Tips on Demonstrating Impact
Mid-Hudson Library System's Return on Investment: Economic Impact Resources 
Blogs/Websites to Watch
WebJunction has totally rockin' demonstrating impact materials that we update annually:
Also check out our section on Funding Strategies that has a lot of other, more specific articles and contributions from WJ members in this area.
Specific Blog Posts/Articles/Books to Check Out
Dialog Quantum case study on ROI author Marilyn Bromley, Library Director, BNA, Inc. http://quantum.dialog.com/q2_resources/casestudies/roi.pdf