If you are in need of publicity and/or buzz for your service or company, Izea is definitely your one stop shop. You can get everything you need from the various social media advertising they offer. They have products sampling, blog posts, and blog sponsorships just to name a few of the offers you can do.  I have been on both sides of the campaigns that can be run;  I have run some of my own opportunites for bloggers, and I am a blogger myself.  The Izea staff is great — if you have any question, they are great to help you get exactly what you want.  Izea now has two marketplaces you can choose from — PPP and Social Spark.  PPP allows you to pick segmentation and any blogger who meets your criteria can choose your opportunity.  Social Spark is more of social networking site.  You are able to set up blogrolls and street teams and choose which bloggers can take you opportunity.  There also is the marketplace like at PPP that allows anyone to take your opportunity.  You can set it up that after your opportunity is full that people can request a slot.  They will tell you why they should blog about you.  It is great way for you to find bloggers that missed out on your opportunity but still are a good fit for you.  They also have dynamic pricing where instead of spending all your money in one day, you can choose a daily spend.  These are just a few of the advantages of working with Izea.  I highly recommend trying them out if you want to advertise!