Using DOS-like commands
There's a package called mtools which is included with most of the distributions out there.
There are several commands for basic DOS stuff. For example, to directory the floppy drive, type mdir a:. This is rather handy--you don't need to mount the floppy drive to use it.
Other commands are: mattrib , mcd, mcopy, mdel, mformat, mlabel, mren (rename), mmd, mrd, and mtype.
This doesn't work for reading from hard disks. In that case, you would add entries to /etc/fstab, drive type msdos for fat16 partitions, and vfat for fat32.