Anyone have recommendations for ad servers? Particularly ones that are compatible with single-page JS web apps (e.g. page context changes, but not necessarily page refreshes)?

I know of two: Google DFP Small Business [1] and iSocket [2]. I'm fairly confident that Google DFP plays nice with AJAX sites

[1]http://www.google.com/dfp/info/sb/index.html [2]https://www.isocket.com/