1. A computer-based method for use in geotargeting online advertisements to users of search engines, comprising: providing a geographic keyword generator running on a computer communicatively linked to a digital communications network; providing a spatial database in data storage comprising a plurality of geographic keywords; from a client node linked to the communications network, receiving a keyword request including location data for an advertiser; operating the geographic keyword generator to determine a service area based on the location data; with the geographic keyword generator, retrieving a set of the geographic keywords from the spatial database associated with the determined service area; and reporting the set of geographic keywords to the client node for use in the geotargeting of the online advertisements.