Any way to add notes to powerpoint/docs ?

hello, thinking of adopting ipad in meeting room environment and trying to figure out if possible to add notes to presentations on ipad.

the notes functions in books purchased in books works great, but i dont think you can add notes to a pdf file imported into ibook.

Im looking for some way to add occasional notes to a ppt file viewed via ms sharepoint rather than coverting docs to pages/notes for editing.

any (good) ideas gratefully received.
TIA