http://www.irs.gov
2. Quicken.com Taxes
http://www.quicken.com
3. IntelligentTaxes.com
http://www.intelligenttaxes.com
4. Tax Analysts
http://www.tax.org
5. TaxWeb
http://www.taxweb.com
6. TaxPlanet
http://www.taxplanet.com
7. Tax Guide For Investors
http://www.fairmark.com
8. TaxKit
http://www.taxkit.com
9. TaxHelpOnline
http://www.taxhelponline.com
10. Tax History Project
http://www.taxhistory.org