A different and interesting project! looking forward to see it working, and the advantages that it brings for us, average BTC users. I believe we can't make a lot from here, but it might increase passionates for javascript to do new things, which may make the technology evolve even more.
Maybe it could be partnered with Augur.net to have people win pools, with such pools containing millions of members. I suspect that this would be the only way to get enough people interested. No one is going to donate their CPU time in exchange for a Satoshi or two.
This (or similar) was in the news some weeks/months before, and if you won't have really high traffic than it doesn't worth the try. Also, some antivirus software are detecting the script as a malicious one, so it will notify the user about the background mining, which is not the best for your reputation...
