What are ideas for project that are useful for the society?

A lot of engineering students are looking for project ideas that are useful for the society. I thought I'd start making a list along with summary so that our fellow engineering students can build upon those. 

Project Ideas for helping farmers

1. Smart irrigation system: Can there be a smart irrigation system that will control the flow of water? It could be Internet-enabled to inform the farmer about the status of the system via SMS. But let's think beyond that - the main issue is water conservation.

The smart irrigation system could help save water by regulating it. 

2. FarmerBot: Think of an agricultural robot that can help with small tasks. It could be a completely mechanical system or eletro-mechanical system that would help farmers sow seeds or pick fruits. 

3. PasteKiller: A smart sprayer that could regular the amount of pesticides being spread on the crop. It could contain bio organic materials. Perhaps - you'll need some help from Chemical engineers.

4. Vegetable Slicer Bot: This could be an electro-mechanical project that would help farmers cut the vegetables so that they are market-ready. 

5. AutoPacker: An automatic packing machine that would help farmers with packaging of the produce. It could help save time and efforts and help improve overall efficiency. 

Lot of interesting ideas are discussed here: #-Link-Snipped-#

Project Ideas for Public Safety

1. SkyWatch: An array of CCTV cameras strategically located at places to keep an eye on burglars and thieves. These could keep watch on the areas that aren't guarded. Your project will have to aim at solving the costs problem.

2. Smart Stick: Often the blind people find it difficult to cross roads or find their way. The smart stick could offer audio navigation and also alert the others who are fast-approaching the user. Perhaps it could send out an audio alarm along with flash lights to alert others. 

3. StaySafe: An automatic distress alarm system that will trigger SoS message to near and dear ones - and also inform the police in near vicinity. Even the kids should be able to use it. 

I will add more later.