Get it from http://get.adobe.com/reader/download/?installer=Reader_9.5.5_English_for_Linux_(.deb)&standalone=1

Of course this won’t work right away on 64 bit Ubuntu (and possibly other linuxes as well)

With Ubuntu 12.10 and above you are able to load i386 packages adding :i386 to the package name and you will need these to prevent similar following messages:

$ acroread 
/opt/Adobe/Reader9/Reader/intellinux/bin/acroread: error while loading shared libraries: libxml2.so.2: cannot open shared object file: No such file or directory
$ acroread
/opt/Adobe/Reader9/Reader/intellinux/bin/acroread: error while loading shared libraries: libstdc++.so.6: cannot open shared object file: No such file or directory

What you need are these:

sudo apt-get install libxml2:i386
sudo apt-get install libstdc++6:i386