list certan mediatypes in a list, page or post.

I was woundering if anybody know how to hack wordpress to list all mediad-ocs of certain types (pdf, doc & txt) on a page or post?

I’ve just started get my hands dirty but i think im in over my head…
(if therse any help – your’e only supposed to see the file-list if your’e logged in.)

/Manny