Unhearit – get that d@mn song out of your head
We created this site for those of you that have a song stuck in your head and you can’t get it out no matter what you do. Using the latest in reverse-auditory-melodic-unstickification technology, we’ve been able to allow our users to “unhear” songs by hearing equally catchy songs. So really all we’re doing is making you forget your old song by replacing it with another one… sorry.
They also have a mobile app. Highly useful.
Reit This Way 
I have read that the reason a song gets stuck in your head (that phenomenon is called an earworm) is that you have not heard it, or sung it to the end. Supposedly if you sing it, or listen, all the way to the end, you will forget about it. Something about your brain cycling it to try and finish it (I think that's called a brain itch). Let me know if it works for you. Thank goodness it almost never happens to me but I don't listen to songs with words.