Apvlv is a PDF Viewer based on GTK and poppler which uses Vi-like keybindings.
For example, <Ctrl-f> to forward page, <Ctrl-b> to previous page, 'k','j','h',
and 'l' to scroll a page up, down, left or right.  Typing '50' and <Ctrl-f> 
will go forward 50 pages; typing '30' and <Ctrl-b> will go previous 30 pages.
Apvlv can support viewing a directory as contents of a pdf document.  
Press 'k' or 'j' to move selected up or down, 'h' or 'l' to collapse or 
expand a dir, and pressing 't' will open the selected document in a new tab.