Have you ever gotten error messages such as the following when running commands such as apt-get?

perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
	LANGUAGE = (unset),
	LC_ALL = (unset),
	LC_CTYPE = "en_US.UTF-8",
	LANG = (unset)
    are supported and installed on your system.

I’ve had this problem quite a lot on my VPS boxes on Linode and SliceHost. The solution is simple, simply run the following:

locale-gen en_US.UTF-8
update-locale LANG=en_US.UTF-8