Here are sites from which you can download free PDF readers for different platforms:

Platform	Program
Amiga	APDF
BeOS	BEPDF
DOS 6	Xpdf
FreeBSD	Xpdf
GNU/Linux	Adobe Reader or Xpdf
GNU/Linux - Debian Package	Xpdf
Mac OS X	Adobe Reader or Xpdf
Microsoft Windows	Adobe Reader or Xpdf
NetBSD	Xpdf
OpenVMS on Alpha	Xpdf
OPIE (iPAQ/Zaurus handhelds)	qpdf2
OS/2	Xpdf
Palm OS	PalmPDF
Psion	Apdf
RISC OS Acorn	!PDF
Solaris 2.x on SPARC	Xpdf