Map technologies for the web (such as Google Maps)

Question

Ok so basically I am talking with someone about building a way for users to post locations to a map and have a pin over the location.

I know Google Maps can do this

Answer 1

I know this is an old question, but for those just stumbling on it now... Here is a list of various free and open web mapping technologies:

https://github.com/erasmus-mundus-geotech-master/open_source_geospatial_technologies

Which one is best for you depends on what you want to do. For collaboratively adding pins to a map, I would also recommend Google Maps, or roll your own app with Leaflet.js!

Full disclosure: I am one of the main contributors to the list above.