The United Nations Office for the Coordination of Humanitarian affairs (OCHA) has created a set of 500 humanitarian-themed icons, which they are making available free of charge.
This might not sound like a big thing, but it’s incredibly helpful when you are in the middle of an emergency and you quickly have to pull a presentation together, or when you have to create a map with the locations of distribution sites, latrines, offices, etc. Besides, if a lot of people start using these icons then you might actually have consensus on what the various symbols mean – standardization is your friend.
The icons are available for free on ReliefWeb and the Noun Project, but I recommend you go to Reliefweb, because the Noun Project seem to contain only 88 of the 500 icons.
ReliefWeb offers the icons as PNGs, embedded in a .docx and in editable vector format. In addition to the library of symbols, the ReliefWeb page also contains a library of country outlines – another thing that can come in handy.
You can download the icons and maps from this page.