NFOView

NFO files, and ASCII text Viewer

A Plain text file that includes information about a software program; contains release notes and commonly includes information about the group responsible for distributing; generally included as part of the program and related files.
NFO files often contain ASCII art. NFOView can render the text characters as the intended graphic. Standard text viewers, are not able to display required characters correctly. Because the once-ubiquitous ASCII code page 437 was never common on the World Wide Web and is poorly supported by most (as of 2007) modern computers, older NFO files are frequently rendered incorrectly in modern web browsers and on modern operating systems (which mostly no longer use code page 437). To display old NFO files as intended, a dedicated CP437-capable viewing software or conversion is required.
Since Microsoft Windows' System Information tool also uses the ".nfo" file extension, Windows users through VMWare or Parallels may unsuccessfully try to open NFO files in the System Information viewer. 

.nfo (also written .NFO or NFO, a contraction of "info", or "information") is a commonly used three-letter filename extension of ASCII or extended ASCII text files that accompany other files and contain information about them. 

Can also open the following files:
•README
•FILE ID.DIZ
•*.ASC