Bash allows you to save some typing by referencing the previous command's parameters via a variable. If you want to reference the first parameter from the previous command you would use
!^ and if you want the last parameter you would use
!$. A real world example would be something like this:
mkdir /long/dir/structure/new_dir cd !$
This would make a new directory and then change to that directory. Alternately you can reference numbered parameters using
!:2 to reference the 2nd parameter.