Couple of quick things that have caught my eye

http://en.wikipedia.org/wiki/Graded-index_fiber

http://rob.rho.org.uk/2011/09/mmmm_pie.html

The surprising truth about what motivates us.

Bitcoin

Unlike other digital currencies, Bitcoin avoids central authorities and issuers. Bitcoin uses a distributed database spread across nodes of a peer-to-peer network to journal transactions, and uses digital signatures and proof-of-work to provide basic security functions, such as ensuring that bitcoins can be spent only once per owner and only by the person who owns them.

My introduction to Bitcoin was via Steve Gibson's "Security Now" podcast; (check out episode 287 here). Along with the Wikipedia article my interest was peaked. Bitcoin seems to be a real, credible digital currency that is cryptographically secure. However - a currency needs to appeal to more than engineers and the economists are up in arms about it - read the very entertaining exchange here.

For the moment Bitcoins are trading for 1 BTC: 20$