I write the odd blog post but have not done any focused marketing. I've gotten a few write ups here and there that provide a trickle of traffic that converts into signups pretty well.
My goal with ThetaBoard is to keep it very simple and flexible. I think I've achieved that (which is good) but it makes marketing more difficult--it's hard to market "unspecific". And having Trello as a free 800lb gorilla doesn't help.
I have a full time job so it's not a huge priority for me right now--I'm just focused on building out new features people request (that make sense). It's growing on its own at a pace that keeps me interested.