Pretty much exactly what the title says.
I tried to keep the functionality simple and intuitive. To use it you select both the camera(s) and the objects that have particle systems and run the tool. The redo panel has a margin parameter that you can use to adjust a bit of a buffer outside the camera space.
The addon generates a vertex group on each object that is weighted to the bounds of the camera(s) view and sets the vertex group as the density vertex group for each particle system on each object.
I may add some more functionality in the future such as a way to decrease the weighting further away from the camera if there is interest.
Link to the addon: https://github.com/HaroldHyrax/PartiCam
It works really well in conjunction with the following particle density addon: https://github.com/jendabek/blender-particles-density
Great for generating trees and grass: