http://psychology.wichita.edu/optimalweb/position.htm Dated 1997/2001. Interesting but probably inaccurate compared to today's expectations, standards and believes. There's the heatmaps etc. scattered around but for basic lay-outs, are there any comprehensive studies out there like the one linked above?
Found one myself already: http://www.webdesignpractices.com/about.html Date from 2002/2003 on 75-300 e-commerce sites.
Instead of searching for studies about website layouts or design you can also try searching for studies on Web Usability. Often times, you can find a lot of the same information. One good book I would recommend is called "Don't Make Me Think" by Steve Krug.