AIDS.gov, a U.S.national project to promote information about the president's National HIV/AIDS Strategy, has developed a HIV/AIDS Prevention & Service Provider Locator that allows you to search for testing services, housing providers, health centers and other service providers near your current location.
AIDS.gov has made the location-based search tool available in a widget for others to include in their own websites. It's available here
This is a great example of developing a new tool and increasing its usability. It would be great to see similar services in resource-poor settings to help both potential patients and health system planners.