These are free tools and guides that are valuble in finding a home...

Find a Home to Buy or Rent
Hud Homes for Sale
Trulia - It seems to have accurate crime information.
Yahoo Real Estate - I really like the Yahoo listings BUT if you choose the option to look for foreclosures, here is a warning, there will be an option for more information to register for a free trail with RealtyTrac, after you enter all your information, name, address, phone number, email address it then tells you on the next page that you have to give your credit card information as well! It then goes on to say that it automatically enrolls you after the 7 day "free" trial for the pay by month subscription. I personally felt duped because they do not tell you this until you have given them all your information! Shame on them and Yahoo!

Home Valuation Tools:
HomeSnap - Nice.
Zillow - Estimates home values. Uses tax assessors values as far as I can tell. I like it.

County Tax Auditors:
Cherokee County, GA - Real Estate Search
Wayne County - GIS

Home and Apartment Rentals:
Apartment Finder
Apartment Guide - I like this apartment search the best, they present the most listings and I like the interface.
Every Apt Mapped - I like this site, while I don't think every apartment is listed, I think most are listed. I especially like the map that has shows all the apartments and the sorting options.
Rental Houses Vey nice, I especially like the option to see the results of your house rental search via Google Maps.
RentoMeter - Compare your rent to other rentals in your surrounding area or any other areas.Find out if your paying too much for rent.

Guides, Statistics:
AirNow - Air Quality reports and forecasts
Area Vibes - Want to know the best places to work and live?
Census Data/Maps
City-Data - Good!
Cobb County Department of Safety - Reliable search for crime in Cobb County.
Crime Mapping
Crime Reports
Georgia Flood Map
Georgia Offender Search
Home Advisor - Environmental info for US.
Spot Crime - Check out crimes for any city. Nice.