Free Apps:
US:
http://www.apple.com/itunes/charts/free-apps/
Other countries:
http://www.apple.com/euro/itunes/charts/apps/top10appstorefree.html
Paid Apps:
US:
http://www.apple.com/itunes/charts/paid-apps/
Other countries:
http://www.apple.com/euro/itunes/charts/apps/top10appstorepaid.html
As far as I know there is no charts for Brazil… 😦