Being able to kill and yank rectangles in text is an incredibly handy tool -- one of those tricks you can't imagine is useful, until you learn about it, and then, your life is incomplete without it.
Say you have:
aaa bbb ccc
aaa bbb ccc
aaa bbb ccc
and you want to move the 'b' block. So you mark from the first bold b to the last bold b (this looks like you're marking the entire block, but fret not) and type: C-x r k. This deletes the block and closes the gap.
Now you move to where you want the top left corner of the b block to go, make 3 lines of space below and type C-x r y, to retrieve the 'b' block and the job is done.
Happy editing!
