ResourceShelf
from Diigo
ResearchBuzz
Pew Internet & American Life Project Report: Search engine use
Nielsen NetRatings Search Engine Ratings
splunk'd
Pipl - People Search
The Free Keyword Tool from WordStream - Free Keywords for SEO, AdWords, & Blogging
Software: Business & Nonprofit | Reviews and Top Software at Capterra
Top 1 Million Websites and the Top Level Domains used to Build Them | Research gTLDs, ccTLDs and IDN
AnswerThePublic.com: that free visual keyword research & content ideas tool