All the easy oil is gone. Now, it'll be harder to reach, and to buy from unstable foreign governments.

Freakonomics Radio's Stephen Dubner talks about the idea of "conspicuous conservation," where people indulge in certain earth-saving acts as a way to show off that they care about the environment, and in turn, benefit socially.

There are reports that Twitter is looking to buy Tweetdeck for $50 million. That app feeds off of Twitter and makes it better.

Microsoft co-founder Paul Allen discusses his tempestuous relationship with Bill Gates, and how he feels about Microsoft now.

Once Japan shuts down that plant, they will have to contend with rising carbon emissions from switching to fossil fuels.

Standard & Poor's alert that it might cut the U.S. credit rating should have sent government bond prices lower. So why have Treasurys gained?