Categorizing pages?

I run a very large site offering live and rare music downloads as well as photos and press scans, etc. I’m having a problem between pages and categories, however. It’s hard to explain but pretty easy to see if I show you:

https://fansite.theimmortalityproject.com

On the right hand menu you should see a heading called “Library”. Underneath it is a category called “Press”. If you click on it, you’ll find a ton of subcategories (probably more than are useful but that’s another story). If you scroll down you’ll also see a heading called “Navigation” with a page underneath it called “Limited Edition”. Basically, I want to be able to put “Press”, which is a category, and “Limited Edition”, which is a page, under the same heading. The way they’re separated now is really counter-intuitive.

I’d also like to do the same thing for the category “Photos” under the heading “Media” and the page “Photo Galleries” under the heading “Navigation”. How can I make this work? As near as I can tell, there aren’t any plugins to accomplish it, but maybe I’m not looking in the right place?

Any help is greatly appreciated!!!

Ava