I am involved in hiring an ASP.NET develover for our company. I found a few sites that listed interview questions. Below there are links that I found useful.
http://srini-aspnet-tour.blogspot.com/2008/12/interview-question-part-5.html (thanks to srini)
http://www.hanselman.com/blog/CommentView.aspx?guid=2d2fae59-a589-4c43-b6a5-b6ebc1a9eafd (too complicated)
http://www.megasolutions.net/kb/ASP_Net_InterView_Questions_1a.aspx (some of them are quite good)
On my question about Session State two people answered, that they try to avoid using Sessions because of big memory consumption. IMHO, this should not be considered as major factor for architectural decision, if you need to keep state between pages.