I've written a desktop app using C# WinForms and I'd like to try using ads to generate revenue. Ad libraries exist for mobile platforms but I haven't come across any which can be used for desktop applications. Do any exist? I looked into AdMob, and it looks like there was a point where there was a desktop SDK, but presently AdMob is mobile only.
Yes, I've already done that. If you look at the results from your search you will see they are for mobile platforms. There are some hits which state they support desktop but when you go to their site (like Crisp Media) they in fact only support mobile. So if you know of any ad platforms which actually support Windows desktop, I'd like to know their names.
Truthfully, it's rare to see ads in a desktop app. I don't think you're going to find anyone with any experience in it. There may be 8,000,000+ members here, but only a handful of those are regulars here and answer questions.
You are most likely doing your own research on this one.