John Langdon is a typographer who has become famous for his ambigrams. An ambigrams is a word or words that has some sort of symmetry, frequently a rotational or mirror symmetry.
Langdon’s work became well known after it appeared in Dan Brown’s best-selling novels The Da Vinci Code and Angels & Demons. Apparently Brown named the protagonist of these novels, Robert Langdon, after him.
Recently I discovered that John Langdon is an alumnus of the college where I teach!
Inspired by this, I decided to try my hand at making ambigrams of my name. Here they are. I’ll put my two favorites at the bottom.
David (mirror symmetry):
David (mirror symmetry):
David (rotational symmetry):
Dave (rotational symmetry):
My last name, Richeson (mirror symmetry):
I also discovered this cool ambigram generator.
(Confession: I found this exercise very addictive. They are really fun visual puzzles. I think I’ve found the perfect type of doodling to occupy my brain during boring faculty meetings.)
David Richeson: Division by Zero 
You should also check out the work of Scott Kim. In particular, I highly recommend his book Inversions.
Thanks for the tip! Those are great.
Really neat post! As you can see, I totally stole, uhhh, pointed people in your direction. [I also apparently was incapable of spelling ambigram correctly, though I did go back and try to fix that two seconds after I posted].
(When I was reading Angels and Demons I got to the point where the guy found the inversion and talked about how everyone thought that was impossible to do, and I was so upset at that incorrect information that I was unable to read any further. TwoPi said the book got better after that, though.)
How long do the ambigrams take to generate by hand? I tried just 2 of my students in Spring 2008, and spent the better part of an hour on each. One reflectional read MattBachmann with the nn becoming the capital M, for example.
One more question. I thought that Scott Kim coined the word “inversion” before the word “ambigram” was coined. Am I right? If so, I think we should honor the master.
Gene,
I think I spent several hours making these. The Pie≠3.14 ambigram (inversion) took about 10 minutes (although that one is crude and was made to work).
I think you’re right about the history. According to wikidpedia Kim used the term inversion in 1981 and Douglas Hofstadter was the first to use the word ambigram, which he says dates back to 1983-4.