Know-How Exchange : Advertising/PR

Is there a source for ads that I can display within my native Windows/Mac application, as opposed to within a web site or a mobile application? Not looking to embed a web browser widget within my native application as that would violate the terms of service of the DSPs I've seen. Also not looking to install a browser toolbar or other installer-related technology. Just want a source of ads I can display within my native application, just the way AdSense works for a web site except it's for my native application.

I've noticed with some interest that this is common with native mobile applications, but I see no examples with native desktop applications. Wondering about why such a dichotomy exists, and more importantly, is there any source for such ads?