Lack of UI Rules

I have been looking into User Interface design a lot recently. Whether it is in relation to my own projects or in conversations with others, the general conclusion is that there are no set of rules for how one should proceed with designing a computer based interface. There are a few general guide lines but, even those are often not agreed upon or contradictory.
So I set about doing a proper search. I found sites like asktog.com and Alertbox but both seem to focus on websites that sell things. This is not the industry I'm in, either personally or professionally. If anyone knows of some good guidelines or people doing research in this field, leave a link in the comments.