Was it ever revealed who ordered the pizza Fry delivered for "I.C. Wiener"?
In the fourth season it was revealed that Nibbler called in the pizza using the name 'I.C. Wiener'. It was a trap placed for Fry so that Nibbler can push him into the machine. The Nibblonians needed him to stop the Brains, but he was born too early.
As to who actually receives the pizza, in Bender's Big Score, Fry himself ends up eating the pizza and in the first Anthology of Interest, Zoidberg claimed to be 'I.C.Weiner'.