Sharing just in case any nugget from this lively discussion would be of use somewhere.
Some points: Consolidation, resource library, getting the site's good stuff out there on Facebook and whatever other platforms exist, to draw people in (maybe simpler for single-army forums, maybe not). Lots of detail tweaks. For sites other than CDO I'd also stress the need to compile resources and gems in handy sections (e.g. a dedicated Tutorial section like on DakkaDakka) and try out some get-together events, e.g. contests (which tend to work over time since they exploit human competitiveness). Of course the conditions discussed are CDO's own, but some common ground may still be found, possibly.