This addon adds a set of operators which help when dealing with curved shaped meshes.
Core functionality aims at working with edge loops, but there are also a couple of tools which work on vertex selections too. The main workhorse is the set flow operator which helps to fit an edgeloop to the curvature of the surrounding mesh.
Check out the documentation for an overview of the supplied tools.
This extension does not require special permissions.
One of my most useful tools! This tool practically allows you to just do subdivision loopcuts anywhere. Insane!
Why is this not in Blender?