Forbes' 18th annual roundup of billionaires is booming -- even as the economy has been slow. With only 476 billionaires last year, the count is now up to 587, and analysts speculate that the growth is tied to Russia's growing oil industry and Bush's tax cuts on dividends.

In the top slot? Bill Gates. Ranking No. 1 for 10 years running, Gates is now worth $46.6 billion. In relatively close second is Warren Buffet, who's pushing $43 billion.