All you do is type or paste an address or Google Earth placemark into it & it tells you what map book, page, & area of the page it's on (Thomson Guide to Phoenix, Page 34, section D-4, etc.).
This widget allows you to type/copy an address and with one click turn it instantly into the appropriate page and quadrant (e.g. F-5) of a map book. GPS Insight is constantly adding new supported map books and encourages customers to let them know which ones they want supported in the near future. Great tool!