Income Tax Return Forms, Instructions and Help

From the IRS: 

Tax Forms and Publications
Instructions for Tax Forms
Previous Years Tax Forms, Publications and Instructions
2007 Tax Forms
IRS 1040 Form 

By State: 

Alabama Department of Revenue
Alaska Tax Division
Arizona Department of Revenue Home Page
Arkansas Department of Finance and Administration Tax Guide
California Tax Service Center
Colorado Department of Revenue
Connecticut Department of Revenue Services
Delaware Division of Revenue
D.C. Office of Tax and Revenue
Florida Department of Revenue
Georgia Department of Revenue
State of Hawaii Department of Taxation
Idaho State Tax Commission
Illinois Revenue
Indiana Department of Revenue
Iowa Department of Revenue
Kansas Department of Revenue
Kentucky Department of Revenue
Louisiana Department of Revenue
Maine Revenue Services
Maryland Comptroller
Massachusetts Department of Revenue
Michigan Department of Treasury
Minnesota Department of Revenue
Mississippi State Tax Commission
Missouri Department of Revenue
Montana Department of Revenue
Nebraska Department of Revenue
Nevada Department of Taxation
New Hampshire Department of Revenue Administration
New Jersey Division of Taxation
New Mexico Taxation and Revenue
New York State Department of Taxation and Finance
North Carolina Department of Revenue
North Dakota Office of the State Tax Commissioner
Ohio Department of Taxation
Oklahoma Tax Commission
Oregon Department of Revenue
Pennsylvania Department of Revenue
State of Rhode Island Division of Taxation
South Carolina Department of Revenue
South Dakota Department of Revenue & Regulation
Tennessee Department of Revenue
Texas Comptroller of Public Account
Utah State Tax Commission
Vermont Department of Taxes
Virginia Department of Taxation
Washington State Department of Revenue
West Virginia State Tax Department
Wisconsin Department of Revenue
Wyoming Department of Revenue