I have been lucky enough to have some fantastic friends out there also looking for ways to advertise. A friend of mine by the name of Claudio suggested I take a look at 2 ways he has found.
Tweib - A social network site specifically designed to advertise.
Easydownlines - A site that will help build your downlines for you.
I also have found some more myself:
|24/7 Backlinks - A site where you can advertise to backlinks.
Paid To Build Your List - A site where you can get paid to grow your list.
This next one is NOT FREE but I have found it so effective with my own advertising that I thought I must share it with you.
AdFly - A site where you can advertise and also shorten long URL's. The URL shortening is totally Free.