Here is one (very funny) song out of many, many more which Jonathan Coulton has made available under a Creative Commons license. "Betty and Me" is a great, hilarious song. Pay close attention to the lyrics ;-)
If you like the songs, please consider buying one of Jonathan's CDs. He also has a nice campaign up currently:
This is sort of a protest - I will write and record one song a week and post it on Friday from now until someone starts paying me to do it. I guess technically then I will need to keep doing it, but you see what I’m saying. None of these are on a CD yet, so if you like them and you want more, please donate to me whatever you think is fair so I can keep doing them.