Piphilology is the practice of writing such that the number of letters in each word corresponds to a digit of pi. Words of at least eleven letters correspond to two digits of pi. Some examples of piphilology are:
Pie. I wish I could determine pi. "Eureka!" cried the great inventor.
"Christmas pudding, Christmas pie, is the problem's very center!" (Also found starting with "How I wish I could recollect pi.")