Inherit and add permissions
Extend the "inherit" behavior of SharePoint security role assignments to also allow for "inherit" + "add", instead of "stop inheriting" + "add".
Right now you can either inherit or break the inheritance of permissions. My idea is to allow for combining the two, just as Windows does with ACLs.
Nathan Wright commented
Yes! Please! I have many use cases where our users want to share a file or folder in a document library with someone--but nothing else in a Site Collection. We really should be able to do this without breaking inheritances. Please make this happen!