I have made up a top-down 'map' of knowledge by compiling A-Z lists of wikipedia articles into wiki-books (but it's for the sciences rather than philosophy).

I've found that the general idea is very effective for learning any subject. Try to pick out all the central concepts or ideas for that subject and complie an A-Z list of these concepts. Generally, the length of the list should be between 50-150 concepts. (Less than 50 concepts, you don't have enough for an effective over-view, more than 150 concepts, you have too much).

Once you have the A-Z list of concepts that provide an effective over-view for the subject, you can then 'drill down' and make up further lists of sub-concepts to get more details in a hierarchial index scheme.

To give you an example, here's the list to my wikipedia A-Z list that gives you an over-view of the subject 'Programming'