Been having a lot of inspiration lately - I hope it's good
MakerChain - open sourcing physical goods making and encouraging localized microfacturing
Problem: The current materials economy is wrecking the planet.
Concept: create a decentralized "app store" of "things" that a person can make themselves (with 3d printing or membership at a hackerspace) or have made by a local craftsman or microfacturing facility so that manufacturing of goods doesn't have to get offshored to wherever the highest concentrations of poverty and cheaply exploitable labor happens to be, and the fossil fuels used to ship the goods all over the world can be curtailed significantly.
People with designs for products; anywhere from the idea stage all the way to prototyped and proven specs submit their "thing" to the blockchain. Other users up-vote and down-vote ideas they like. If someone has an idea for a change in the design, or an additional layer to an incomplete idea, a new branch of the chain is created when they submit their idea. Those branches get up-voted and down-voted as well.
End users can download a set of plans and join a local maker-space/hacker-space to build the thing themselves, or hire a local micro-facturer to build it for them. The plans are open-source and available to all for free, but if an individual appreciates them, they submit a tip and the individuals who contributed to the idea get cuts of the tip (similar to quirky). Lots of groups are working on putting mini makershops into shipping containers so they can literally be placed wherever there is need for one (everywhere). All of the businesses that support this economy (Hackerspaces, Makerspaces, microfacturing facilities) can offer discounts to their customers for paying in MakerCoin in order to support the value of the coin and financially support the work-effort of the miners, and a central foundation can repay those discounts so the business doesn't need to eat the loss.
Foundation can also offer grants (in MakerCoin) to makers or inventors who come up with new, less resource heavy ways to make things. Or ways to make something out of more recyclable materials than they currently are - anything geared toward *actual sustainability*.
Full disclosure: I am working on founding a hardware design and microfacturing coop, so I obviously have some specific financial interest in this type of idea. Closed-source goods, however, I feel are part of the problem of the materials economy, so, if this idea has legs, I would be inclined to develop products specifically to release them into an open source network - and then get paid in tips by those who think they're good products and also offer the service of producing the product for them if they're local enough.