I'm a big fan of HSBI. I started using it as a reward on my Punday Monday series nearly since its conception. It's a weekly contest and we're approaching the 500th week, so it's been... 9-something years? can that be right? 8 years at least. I also helped found the Freewritehouse community, which I think has been excellent at driving creation and engagement, encouraging folks to write every day, and supporting writers at all points along their journey.