Sounds like an INI FILE to LIST type of thing (defun INI->LIST ( FileName ) ...), and I believe (or logic suggests) it has already been done (several times over).
However, if it's for the sake of an exercise it would be fun, with the strict provision that the participants draw solely from their own grey matter; no other forums, newsgroups etc. used as resources.
If I had the time I would have kicked this off with an outline of all the perceived required functions, but alas.
I would say that you'd want the ability to read from, publish to, replace, find ...
... gotto head off to work now, doh!