Need help with custom interactive mapping

I'm trying to add a map to my blog that anyone can add their own data to. The result should be a map covered in markers that can be clicked to show user data.

I've tried google maps, but they don't seem to have a feature that lets all other users add to the map.

Additionally, I need to be able to moderate user entries to block spam.

I tried searching already, and asked this question on another mapping forum, but haven't gotten any results.

I was hoping that there was someone here who can point me to a service like that.

THANKS!!!!