I'm building a location-based advertising solution for a client. The advertisers have a self-service portal where they can manage their campaigns. I need to be able to set a centre point and a radius showing the area the advert can be shown in on Google Maps/Bing/Yahoo!/Cloudmade/Whatever maps. I can put a marker on a map, and I can even draw a circle. What I don't know how to do is to have a circle with some sort of marker I can drag in and out, making the circle bigger or smaller. There must be a standard bit of code to do it, but I've no idea where it might be. Has anyone done anything like this?
Thanks
