Here are very useful maps which help me locate things when I come to devising my agriculture plans. They can be useful for other aspects of the project as well
 distribution of the population
agricultural potential of the land
  climates in Brazil
 Reliefs of Brazil
 Parks and biologic reserves
 Transport infrastucture
 Amazon watershed and river system

  Brazil seen from space: GIS system   : this site is extremely useful to me because I can see exactly at what latitude and longitude a specific farming region is or whether a zone I'm intersted in is already used. I can see where are the roads, how the river flows... With this I will be able to choose a very precise patch of land for my farm and it helps me know characterize the composition of the soil from Land's soil database.