Ambigram n., - a word or words that can be read in more than one way or from more than a single vantage point. (from the Latin: ambi=both + gram=letter)
(These have 180 degree rotational symmetry)
Bobigail
Miki
Miki (English and Hebrew)
Yoz
Scott Kim's Inversions
John Langdon
Ambigram.com
