Drive traffic using EntreCardThis is a wonderful place that allow you to place your banner ads on some others sites. just you have to place there ads on your blog. most of the expert bloggers are using this to drive traffic. because it hasn't a uncompleted look as other ad exchange iframes.
There is a credit system as a alternative for money. you just have to earn some credit to display ads on others sits. the good thin is you will get credits when some one click an ad on you blog. also by referring peoples.