Robert M. Patton, Christopher G. Stahl and Jack C. Wells have published "Measuring Scientific Impact Beyond Citation Counts" in D-Lib Magazine.
Here's an excerpt:
The measurement of scientific progress remains a significant challenge exasperated by the use of multiple different types of metrics that are often incorrectly used, overused, or even explicitly abused. Several metrics such as h-index or journal impact factor (JIF) are often used as a means to assess whether an author, article, or journal creates an "impact" on science. Unfortunately, external forces can be used to manipulate these metrics thereby diluting the value of their intended, original purpose. This work highlights these issues and the need to more clearly define "impact" as well as emphasize the need for better metrics that leverage full content analysis of publications.