Writing upside down can be quite useful. For example, as I stated in my original article on this subject, some uses for this facility could be:
Book covers.
Novelty items.
Special effects in a story.
Greetings cards.
Yet another use, as someone pointed out to me yesterday, would be to put the answers to a test or quiz at the bottom of the test paper.
A good website for creating both upside down and reversed text is http://www.upsidedowntext.com, shown below:
Upside down text, by Terry Freedman
In the two examples below, the first one is copied/pasted from the missle box above, while the second uses html code.
˙ʇxǝʇ uʍop ǝpᴉsdn ƃuᴉʇᴉɹʍ ɟo ʇsǝʇ ɐ sᴉ sᴉɥ┴
You can also copy/paste straight into Word:
Upside down text in Word, by Terry Freedman
So, a very useful facility, and completely free.