If you work in corporate IT, then you've probably had users come across sites that appear to be things like Acrobat Reader, Google Earth or some other application.. but are in fact a deceptive way to install some other software (typically some sort of adware). I call this "slimeware".
This list of sites are (in my view) [CSV] offering applications of limited use that you might want to consider blocking. Some example sites trade heavily on well-known names like Avast, Yahoo Messenger, Nero and other well-known apps. Quite a lot of these are sourced via MarketBay. Scroll down for some sample screenshots.
The list includes over 1000 sites of dubious value and a much shorter list of IP addresses (below) which might be easier, plus MyWOT ratings as a guide to the nastiness of the sites. You can download it from http://www.dynamoo.com/files/slimeware01.csv