Google maps

8a.nu website has google maps where you can simply to this map add whatever you want.

http://web.8a.nu/crags/MapCrags.aspx?CountryCode=GLOBAL

I want to have something similar on my wordpress blog. I want if reader add point to the map on my blog.

Do you know how to do it. Does exist plugin on google maps? Do you know how 8a.nu website made this function – google maps?

Please, help me!!! Thanks.

Sorry for my english :), I am not native speaker.