Earworm

As per the 2/28/03 episode of KUOW's Radio Rewind, the word "earworm" is a translation of the German word for the phenomenon.

http://rewind.kuow.org/Archive_Get_from_db_test.asp?Date=2/28/03

The clip starts at 40-minutes into the program.

It's a great show - I highly recommend it!