Nice concept to visualize.. but browsers are inefficient and inefficient miners => prone to 51% attacks. I don't see the advantage of browser miners, except it's fun to look at.
Interesting concept and implementation. Assuming you can overcome some of the potential discussed security issues with a browser based blockchain, I think there's a lot of potential. One market I see is mobile/web gaming. Developers could run a mining node in the background to generate a profit without needing ads or fees. Assuming mobile nodes could be efficient enough to add up to small micro-transaction profits over time.
Game of Coins