Hi again: Installing cathedral ceilings is a possibility, as is 'curling the edges' of the walls. That is, removing the existing ceiling and ceiling joists, raising the joists and attaching to individual rafters up about 12" from the top plates, then rolling the new ceiling plaster from the wall up the incline of the rafters to the new ceiling joists. This was a not-uncommon practice used to get a little more ceiling height on the second floor of colonial style houses in the 40's and 50's. Unfortunately, this still requires raising each stud wall up to the new height, as well as extending wiring. It would also be the messiest job you will have ever seen, and the cost of having this done will be, I'm sure, quite high.
Sky lites are another option that are good for getting lite into dark places. In, I believe, the Dec issue of This Old House magazine, they demonstrate how to install a sky lite, boxing the lite down through the attic to the living areas below
Personally, I would give up on the raise the ceiling idea. I haven't seen your situation, but I've done a lot of construction and this retrofit would be a giant and expensive headache from the get-go. Perhaps others can share their view. Hope you don't mind mine :-)