As I suggest back on 2009 (http://koha.1045719.n5.nabble.com/Geolocalization-in-Koha-td3069181.html ) it would be very nice if Koha could offer geolocation[0] (maybe using openstreetmap.org or Google Maps API). Having branches spread over a large territory make this feature very useful, making the records of the searched material more near first in the result list. Is possible to add some heuristics based on what people usually search for nearby (as Google does). There are some freely available databases[1], but also is possible to create and improve one over time, based on location established on registered and logged users, associating it with their IP address. Some extra fields for each Library should be added to database (aside code for geolocation and sorting OPAC results) like longitude and latitude on Decimal Degrees, "DD"[2], and a system preference to activate/deactivate this. [0] http://en.wikipedia.org/wiki/Geolocation [1] http://www.ipinfodb.com/ip_location_api.php [2] http://en.wikipedia.org/wiki/Decimal_degrees
To make things easier it could use (also or instead) HTML5 Geolocation API, as "Library Finder" [0] (ResearchWorks from OCLC). [0] http://www.oclc.org/research/activities/researchworks.html
Now that branches table have a geolocation column would be great to sort results depending on user location (based on HTML5 geolocation, IP or user address).