You have to understand that an adf file is not an archive like an lha file, but an image file of a disk. So you don't exactly dearchive them; that's why a lot of programs write them to floppy disk but you can also mount them in a virtual floppy drive; a tool that does that is called Diskimage I believe.
The idea is that this way you can also make files of floppies that aren't DOS compatible. Mounting these disks isn't really usefull in normal WB use though.