For a long time, I have been looking for a way to both collaborate and publish geospatial data and map. Harvard WorldMap may be the answer. It is certainly the best thing I have found so far. Although it is based upon GeoNode and you (perhaps with help) could get your own instance up and running, the key to Harvard WorldMap is that it also aggregates maps from other sources.
With Harvard WorldMap, users can upload layers- including vector (points, lines, polygons) and georeferenced raster (e.g., aerial photos or historic maps) layers. Formats are currently limited to shapefiles and GeoTiffs. Once uploaded, the user must add metadata. This is a very good thing and a vital step in the production and sharing of any type of data, but is often difficult or imperfect for geospatial data.
The user can manage who can view, edit and manage the layers. Until it is ready for sharing, the user can keep it private. If they want to collaborate with others, they can allow only those individuals view, edit or edit and manage permission.
Once added, layers can be downloaded in a number of useful formats (Zipped Shapefile, GML 2.0, GML 3.1.1, CSV, Excel, GeoJSON, GeoTIFF, JPEG, PDF, PNG, and KML). Layers can also be streamed to your desktop GIS program (you are using QGIS, right?) via Web Mapping Service (WMS). This means that, to make other layers in your desktop program you can have the same data as all of your collaborators streaming rather than from a file on your computer.
Layers can be aggregated into maps, for which access can also be restricted or not in the same way as layers. You can add your layers, but you can also use their search engine to find layers that are connected to Harvard WorldMap, such as maps from USGS or from ESRI. The selection is not yet amazing, but I was able to find a few maps for my work in Ecuador that I had not found elsewhere.
Vector layers can be styled by changing the marker shape, color, size and label.
This map can then be published. Here’s a test of some data collected by my students and I regarding charcoal production on the Blue Mountain in Pennsylvania. Take a look. Note that you can change the layers (both my uploaded layers and the basemap).