All the people who got introduced to the wonderful world of ambigramming through the ‘Angels and Demons’ you might want to check these links.
John Langdon
Scott Kim
Punya Mishra
Robert Maitland
Paxy
As Paxy says, a good ambigram must follow the criteria of : Symmetry, Legibility, Aesthetics.
That’s what makes it a piece of art, isnt it? Why wait then? Go ahed and do some ambigramming. Someday I shall do one good ambigram. What about you?