What are some alternatives?
When comparing PowerInbox and Sharethrough, you can also consider the following products
Nativo - Nativo is an advertising technology platform for brand advertisers and publishers to scale, automate, and measure native ads
StackAdapt - Native advertising demand side platform.
Adobe Advertising Cloud - Adobe Advertising Cloud is ads providing a platform that lets your media-related thing to lift on the high note.
AerServ - AerServ offers monetization solution for mobile publishers.
Gold Lasso - Publishers, monetize and automate your email newsletters in new and unique ways.
Engageya - Engageya is a content recommendation tool that offers a reader exchange ecosystem for publishers and bloggers.