.chm files are used for documentation and are generally distributed by Microsoft and other companies that accompanies their product. That is, when they're not using PDF.
Well, Emacs can view those CHM files within its buffer. This page on Emacswiki tells you how to setup Emacs to view chm files. Note that it requires archmage which is needed to extract the chm content and it looks there is no binary for Windows. Unless of course, you'd want to build a binary for the Windows platform. Those with cygwin installed might have an easier time.
Well, Emacs can view those CHM files within its buffer. This page on Emacswiki tells you how to setup Emacs to view chm files. Note that it requires archmage which is needed to extract the chm content and it looks there is no binary for Windows. Unless of course, you'd want to build a binary for the Windows platform. Those with cygwin installed might have an easier time.