In reply to:

is there a word to describe the common condition of having a tune, song, melody, etc., go through ones mind forever (or seemingly forever). The tune is often the last thing I hear on the radio while driving to work, but they can come unbidden in the middle of the day. People think I am strange when they hear me humming "you better watch out; you better not cry; Santa..." in July.


you think you've got it bad? from the Onion:
Ronald DeGaetano, sole survivor of the Jan. 31
Alaska Airlines crash that claimed 88 lives, has had the
1982 Asia song "Sole Survivor" stuck in his head
ever since. "Goddamn it, I can't get that stupid thing out
of my head," DeGaetano said. "After the plane went
down, I was floating out there in the Pacific, thinking about
how I was the sole survivor, and for some reason, that
song popped into my head. Now I can't get it out, and it's
driving me friggin' nuts."
DeGaetano said that if he does not shake the song
soon, he is going to "start wishing I hadn't been the
sole survivor."

[yart alert -- all those who detest yarts, stop reading NOW]
this came up before, and some suggestions were made that you might want to look at...

http://wordsmith.org/board/showthreaded.pl?Cat=&Board=words&Number=2260

...and for those who don't want to have to deal with an old thread, one idea was the German ohrwurm, which translates to ear candy or mindworm.