I just have a very basic design on my computer and print some off as needed. 2-up on an A4 sheet and guillotined.
One way to plug additional services could be to list all services with a tick box next to them. When you leave your normal window cleaning bill, you just tick the box next to window cleaning and write the amount wherever you normally write it.
That way, you can show that you offer other services, but without appearing too pushy.