What came after Z in the English alphabet?

xyz.

Now I've said my ABCs.
Tell me what you think of me.

That's not it at all.

"Now I know my ABC's
Next time won't you sing with me."

The word ampersand is a corruption of the phrase "and (&) per se and", meaning "and (the symbol &) intrinsically (is the word) and".
Traditionally, when reciting the alphabet in English-speaking schools, any letter that could also be used as a word in itself ("A", "I", and, at one point, "O") was preceded by the Latin expression per se ("by itself"). It was also common practice to add the "&" sign at the end of the alphabet as if it were the 27th letter, pronounced and. As a result, the recitation of the alphabet would end in "X, Y, Z, and per se and".

http://en.wikipedia.org/wiki/Ampersand

And?