The filter that prevents more than two results from the same domain showing up in the Google SERPs (one indented below the other). Adding &filter=0 to the end of the URL address after performing a search, will turn the Result Crowding filter off. &filter=0 apparently filters for other things as well, but these things are unknown at this time.

About the Author: Donna Fontenot

Donna Fontenot, aka DazzlinDonna, is an Internet Entrepreneur and SEO, who has long utilized search engine optimization and affiliate marketing to create a successful online business. Her goal as an ebusiness coach is to help others make a living online from the comfort of their homes (and in their pajamas). Her motto is "You'll never shine if you don't glow."