How Is Crowd Size Estimated?

Reports of the number of people who attended Glenn Beck's Aug. 28 rally have varied wildly - from 78,000 to 800,000 people. How is crowd size estimated - and who does the counting?

Katy Perry Goes No. 1

Katy Perry has made a big splash as the summer winds down as her new album Teenage Dream debuts at No. 1 on Billboard's Top 200