• Rainwater harvesting
• Flood control
• Groundwater recharge
• Urban agriculture
• Reducing the urban heat island effect
• Sustainable housing - including passive solar
• Solar hot water in hot climates

Big picture:

• Transportation - bus rapid transit, comparison of Curtiba & Jakarta (esp compare number of buses)
• Sustainable city living

Social:

• Environmental psychology
• Green communities
• Organizing green communities
• Culture and development
• Corruption