Rejigged the "What's best for my game" and such. One of the things I've been thinking about is the issue of framing your sales or how the sale of your game gets framed by customers.
By this, I mean it's important to attach not just products but sometimes ideas or causes to what you're selling. With Indie Game Bundle, it wasn't just a valuable sale with games as the product, there was a cause attached for Linux and Mac buyers (outside of charity). By buying the game, they were buying into a cause - more games to be made for Mac and Linux which lead to higher donations amongst Linux and Mac users, leading to a disproportionately large amount of revenue from them. Much of the discussion around Humble Indie Bundle wasn't just how good the deal was, but by buying this would create better chances for more and better Linux games to come.
In this sense, it's just as important through marketing and other means to make it clear they're not just buying an end product, but supporting something. From the development as already discussed here, but also larger goals like more and better games for Linux. This has sometimes lead people to being happy about being treated like a second class customer (most Linux ports that come years later and are more expensive than the Windows counter part by that point), as they're not just buying an end product.
Make it clear that they're buying into supporting your development, not just a shiny end product. Do everything to make them feel a part of the project, and not just a number on a financial sheet. Do what free software does best: Make people feel involved, informed and like they're having a positive impact.
As always, more feedback and ideas welcome.