I love lists of free/cheap directional resources [sites/approaches] because they expedite my secondary searching, allowing me to more effectively move on to  whatever combination of primary research / humint / synthesis / analysis / recommendations etcetera a project calls for.  I listed a few more foundational/functional ones already, but wonder what areas readers would more be most interested in seeing uploaded / maintained...
It's not like there aren't lists for many of these out there -- but they each have their own spin, and miss pieces... [Not that I would claim to be all inclusive, either..] And some are out of date.  BUT... many lists focus on the "category" of the information like newspaper or directory -- as opposed to the need the source fills. Today, what originally would have be classified as a newspaper site now also offers shopping, or interest group communities, etc. The old boxes don't really provide adequate boundaries to capture what's out there.
Here are some I have planned -- albeit not all at once.  I have the 
basics, but I want to update them... 
- Company rumor / employee venting
 - Patents / intellectual property
 - Other [non-IP] legal / regulatory information
 - Reputation / brand / advertising etc
 - Country-specific information
 - Industry/Product -specific information
 - Indentifying HUMINT sources & biographical background on same
 - Private companies / subsidiaries / NGOs
 - Specialized & meta-search engines, also consolidators
 - Sources of free or inexpensive market research or extracts
 - Web site monitors
 - Publicly available data collected by government organizations -- which is not the same thing as government information. Ditto data from NGOs.
 - Great widgets
 - Financial information
 - Ratings / Rankings
 - Benchmarks & best practices
 - User-generated content that actually has business applications
 - Demographic data
 - Statistics, not elsewhere classified -- especially when times series / trending available...
 
Maybe I'm a bibliographer at heart... But really, what really comes to mind is that old perfume commercial. My version would go something like this....
I can find all the info...
Synthesize it concise ....
Add analysis & insights so nice...
'Cause I rock research -- hire me!