Appropriately, my fascination was inspired by Angels and Demons by Dan Brown. Which will be coming out as a movie soon. I don’t have the cover of the book that I am currently reading here but the illustrated Ambigram title is posted here. Inside the book has the ambigram of “Angels & Demons” and “Illuminati.” This is just Ambigram inspiration eye candy.

“An ambigram, also sometimes known as an inversion, is a graphical figure that spells out one or more words not only in its form as presented, but also in another direction or orientation.” wiki source

Ambigrams are graphic design exercises which  can be created in many ways. It’s created with “with optical illusions, symmetry and visual perception.” They fall into many categories which you can read here. I also read that there isn’t a specific way to create them. Here’s a fun site where you can try to create them automatically (it’s not always perfect)

Resources
Ambigram.net
More about Ambigram on Wikipedia.
Manokan Express
Justin and Hesiman
Early published ambigram by Mitchell T. Lavin in The Strand, June 1908
– Guitar Hero is my personal favorite.