The only other effort I know of is the "fan of hbase" on facebook. Who created that one? What is its goal? Can we somehow combined efforts or even consolidate them? For example, the Twitter updates could be cross posted to Facebook's status of the HBase account (if that is actually an account?) using TweetDeck etc.
Just on Stack's comment, the thing I see is that we need to tackle two audience mainly, the developers and the management. While we are starting to have good documentation on the Wiki for developers I think we could improve to pitch HBase on an "executive white paper" level - so that it will be considered by the decision makers in selection processes.
We have so many "Powered by" entries - there ought to be a lot of material we could use to build case studies. And as Stack says, I think we should not answer the religious question "Why HBase? Why not database A or storage solution B?" - we need to explain why we use it for our particular projects. That alone will show off HBase's features and how someone could make use of it.
I am also suggesting we create a army of volunteers, the "Ambassadors of HBase". I am a - self proclaimed, mind you - European Ambassador for HBase where I offer any company or institution to have me present and advise on HBase. Just for the cost of travel (and accommodation if to far away). Not sure if anyone will make use of this, but it is one more step towards advocating HBase to everyone who is even remotely interested.
The first step is of course selling us through our site. It must answer all preliminary questions a developer or decision maker may ask. Maybe divide the sections into two separate ones, have a generic FAQ, case studies and white paper section and then a developers corner with API documentation, samples, advice etc.
One more issue - and please this is not to blame anyone, you are all outstanding guys - I would suggest to clean up the Javadocs starting with the direct API (or client) classes and then traversing down. That way a new developer has a much better support from say within Eclipse as the documentation of the classes already gets them what they need quick. The lower classes are important too as that will give more people access to the gory details and we may gain more contributors and eventually committers.
If I am off here, please let me know too. I am just trying to get a revolution going.