You have the following:

Scribus - http://en.wikipedia.org/wiki/Scribus (Already in the repository)

LyX - http://www.lyx.org/ (Already in the repository)

Sozi - http://sozi.baierouge.fr/wiki/sozi - A next generation presentation maker that is used as an extension with inkscape to create amazing presentations using SVG format.

And apart from Impress you have Draw in the LibreOffice suite.

All of this can export to PDF (Which is like a normal thing in Linux but not so normal in Windows since you need X or Y program to do it)

UPDATE - Included Sozi which I find a next generation presentation tool. Similar to Prezi.

Here's my take on it from personal experience. It's a two-step process - convert the PDF into single jpegs, then import the jpegs into LibreOffice Impress. It works best if the pages in the PDF are landscape already.

1.) Make sure the package imagemagick is installed (apt install imagemagick). Put your source PDF into a directory. Then in the terminal, navigate to that directory and run:

convert filename.pdf filename.jpg

This will spit out a jpeg of each page in the PDF. Move the PDF out of the directory to make step 2 easier.

2.) Open Impress. Go to Slide menu, Slide Layout -> Blank. This will remove the "Click to add title" and stuff. Then go to Insert -> Media -> Photo Album. Click add. Navigate to the directory with all your jpegs. Select all the jpegs (if you removed the PDF from the directory in step 1, just press CTRL + A to select all of them). Click Open. The next options depend on what the pages in the original PDF looked like - if they were landscape, you can probably choose Fill Screen, but you'll have to see what works best for your case.