As estimated by Forbes magazine:
1 Warren Buffett US$62 US Berkshire Hathaway
2 Carlos Slim $60 Mexico Telecoms
3 Bill Gates $58 US Microsoft Corp
4 Lakshmi Mittal $45 India Steel
5 Mukesh Ambani $43 India Petrochemicals
6 Anil Ambani $42 India Diversified
7 Ingvar Kamprad $31 Sweden IKEA
8 K.P. Singh $30 India Real Estate
9 Oleg Deripaska $28 Russia Aluminum
10 Karl Albrecht $27 Germany Aldi supermarkets
What's interesting to me is the number of Indians, 4 of the top ten, and the sheer fortunes involved. Albrecht in 10th place has 'only' $27billion, you could never spend that kind of money. Be fun trying though.