The US researcher Benjamin Edelman, famous for his publications about internet filtering in China and in Saudi Arabia, has turned to spyware, and the results of his research are impressive. In November 2004 he did a simple test, to find out how much junk can get installed on a user's PC visiting a single webpage. "In the course of my testing, my test PC was brought to a virtual stand-still -- with at least 16 distinct programs installed. I was not shown licenses or other installation prompts for any of these programs, and I certainly didn't consent to their installation on my PC. (...) Other symptoms of the infection included unwanted toolbars, new desktop icons (including sexually-explicit icons), replacement desktop wallpaper ("warning! you're in danger! all you do with computer is stored forever in your hard disk ... still there and could broke your life!" (s.i.c.)), extra pop-up ads, non-standard error pages upon host-not-found and page-not-found error conditions, unrequested additions to my HOSTS file, a new browser home page, and sites added to my browser's Trusted Sites zone."
Now Edelman has made comprehensive list of 4 of the best-known spyware producers in the US, and their main investors. In total, he tracked over 139 million US Dollar worth of investments by respectable firms.
Benjamin Edelman, Investors Supporting Spyware
http://www.benedelman.org/spyware/investors/