Update for ?:
A single address multiple times is really the simplest thing you can do.
1) Select the size and format of your label, again Avery software
(
http://www.avery.com/avery/en_us/Templates)
can help with that. Make sure your page is set up for columns and rows and fits you page size.
2) Type the address into one of the cells the way you (and the post office) like it
3) Select that cell by pressing shift-key and guiding your mouse cursor across the cell so you have the whole address selected.
4) Press command-c, this takes a copy of the selection into a register.
5) Go to your empty cells of the page and press command-v, consecutively, in all other empty cells. That will leave a copy of that same address everywhere where you place your cursor and press command-v.
Have fun!