The Association of Research Libraries is gathering profile descriptions of its member libraries in order to “to identify similarities and differences among libraries and to identify elements that will be measured for the purposes of an alternative to the expenditure-focused Library Investment Index.” The Library Investment Index is used to create a well-known ranking table of U.S. and Canadian research libraries (see page 90 of the ARL Statistics 2006–2007 as an example.)
Read more about it at "ARL Library Profiles Being Collected."