Add an smartsearch for suggested call number into WORLDCAT
I think it would be extremely useful, and very widely used if you connected to WORLDCAT. This way everyone could find what books are in their own closest library. Also you would not have to add so many individual library databases.
Gensmarts already gives a Call number and title eg.
Call No: 977.1 A1 no. 169 Title:Wills index of Guernsey County, Ohio, 1812-1900 just pass this on to WORLDCAT