A free but not Free PDF viewer provided by Adobe. There are binaries for many platforms, including Windows and Linux versions.

Look here

If you are using Redhat 9 you will need to edit the /usr/local/Acrobat5/bin/acroread (or similar script) and add the following lines near the top

LANG=C export LANG

This is to fix a problem with character sets that will manifest itself as

Warning: charset "UTF-8" not supported, using "ISO8859-1". aborting

This problem occurs if your locale is set to one that uses UTF-8, which many distributions are now defaulting to. Use the locale(1) command to see what yours is set to. See the UnicodeNotes page if you have no idea what "UTF-8" or "ISO8859-1" means :)

On other distributions (such as Debian and Slackware), Acrobat Reader prints out the warning but doesn't abort.

Other PDF viewers you could try include xpdf(1) and GhostView (gv(1)). Both of these are Free software.