Isn't it funny though, how all the little proggies that form the core of Linux, like cat and top and ps and dd and all those things, can provide so much endless entertainment.
I must think of new things to do with cat every other day (that's ConCATinate, as opposed to a member of the family Felus).
And the really odd bit is, that you'd not necessarily find them, or find out their abilities in normal modern day-to-day Linux use. These days you'll only know much about them if you've read a book or just happen to be an oldschool *nix dude, who actually used it for real work once.
example of dd........
Don't want to pay ££££ for Acronis trueimage?
(to backup a windows C:\ to a backups partition mounted in Linux.
dd if=/dev/hda1 | gzip > /mnt/backups/saveass.img.gz
to restore.......
gunzip /mnt/backups/saveass.img.gz | dd of=/dev/hda1
( you can do the same exact thing with cat as well)