One of my friends let me know of this idea a while ago, but I actually have never tried it myself (if anybody wants to, let me know how you do). What he wanted to do was promote his ringtones website without having to pay any advertising bills. To accomplish this, he decided to take advantage of the high traffic over at youtube. Here is what he did.

1) Download a popular music video (check out Billboard Top 40 for ideas)
2) Use video editing software to add a text banner (watermark) at the bottom of the music video saying something like “To download the ringtone for Chris Brown - With You, go to www.ringtones.com”
3) Upload the video to Youtube… make sure to use a good, descriptive title in order to get search results. A good video description will include even more keywords as well as the URL you wish to promote.
Example title - “Chris Brown - With You - Music Video”
Example description - “Watch Chris Brown’s new music video ‘With You’ if you wanna get the ringtone, go to www.ringtones.com”
4) Sit back and watch the visitors come to you.

This method might take some experimenting, but once you get it, the traffic will be good. My friend told me that he got around 3000 visitors per day and could have gotten more if he did a better job scaling it up.