I love ProjectWonderful for advertising my shop online. Anyone with a virtual business knows that if you don't promote, promote, and promote some more that you'll never have any traffic. No traffic means no sales. I'm not the greatest with self-promotion through social networking, so ProjectWonderful works great for me.
Simplistically, you join ProjectWonderful, then bid on ads you'd like to place on various sites. Recently I was asked if I could write a tutorial on ProjectWonderful, and I agreed to do so. I found very quickly that writing about it wasn't going to work, so I made a video walkt-thru. It's on YouTube; here's the link: http://youtu.be/bqLNe-fa7hk
I hope that you find this helpful and can put it to work for you. In case you are curious, my advertising budget is $15 per month.