(updated August 15, 2013)
“HFVExplorer is a Windows file manager that can be used to access files stored on disks that use the HFS file system developed by Apple Computer for their Macintosh computers. It is often used when emulating Mac OS on Windows. It can read / write Mac 1.44Mb floppy disks and can read / write Disk images that are used in Macintosh Emulation.” 1)
The program was developed by Lauri Pesonen in the mid 1990s. It was based on hfsutils by Robert Leslie.
A similar application for OS X is FuseHFS.
The Basilisk II Setup Guide begins with a walk-through of HFVExplorer's basic functions, including the creation of a blank hard disk image, and the copying of some files from Windows to a disk image.
The official documentation (via archive.org) is also very helpful.
Questions can be posted in our support forum.