Consider a rule-based backup system that only saves things that meet certain criteria. This could be a simple test of time stamps or it could include factors such as file type and size (do we really want to back up .o files or humongous data files?).
Several years ago, I created such a backup system for Apple. It worked, but was not easily configurable by non-programmers. Using Meta, a generalized backup system could be created, allowing users to specify arbitrary selection criteria.
More generally, what is missing or wrong in the man pages? Several years ago, I did some simple graph analysis on Apple's (A/UX 1.0) man pages. I'd like to do this again, more completely, folding in metadata from other sources.