NFO Viewer is a simple viewer for NFO files, which are "ASCII" art in the CP437 codepage. The advantages of using NFO Viewer instead of a text editor are preset font and encoding settings, automatic window size and clickable hyperlinks.
NFO Viewer should run on all major operating systems, but is primarily targeted for Unix-like systems (GNU/Linux, *BSD, Solaris, etc). The user interface is based on the GTK+ toolkit and has been designed to best fit the GNOME desktop environment.
You should probably find NFO Viewer via your distro's package management as "nfoview", if not, get the tarball and install from source.