ePDFView

ePDFView is a free lightweight PDF document viewer using Poppler and GTK+ libraries.
The aim of ePDFView is to make a simple PDF document viewer, in the lines of Evince but without using the Gnome libraries.

http://trac.emma-soft.com/epdfview/

Evince

Evince is a document viewer for multiple document formats. It currently supports pdf, postscript, djvu, tiff and dvi. The goal of evince is to replace the multiple document viewers that exist on the GNOME Desktop with a single simple application.

http://projects.gnome.org/evince/

Vindaloo

A PDF Reader. It is currently under active development. Vindaloo runs under Mac OS X and GNUstep. The OSX version that comes as a dmg-file does not require installation of PopplerKit. For GNUstep, you need to download and compile PopplerKit first.

http://home.gna.org/gsimageapps/