I'm looking for an open source platform to host a map that fellow staff could add points and polygons. The points and polygons are to represent job locations for our surveying company. The simpler the application the better as none of the staff come from a strong GIS background.
You might be able to do what you want with Ushahidi:
Its open source and you can try it out from the OSGeo Live operating system DVD or get a demo instance online (hmmm does it allow polygons to be recorded??).
Plenty of questions remain. Who is allowed to enter/edit/delete data on the system? How do users get created and authenticated? Does it need to integrate with a corporate IT system? What per-feature data are you storing?
There may be spatial addons for WordPress or other popular content management systems that let users create spatial data. If I had to build an application for you from scratch I'd probably use Django and GeoDjango as a web framework.