Make a individual tax estimates or payments to the IRS or view your balance online
EFTPS: The Electronic Federal Tax Payment System
Make business tax and payroll tax deposits and payments
Check the status of your IRS refund
Social Security Administration
Learn how the Social Security Administration can help with your retirement, Medicare, disability, survivorship and other benefit questions.
U.S. Small Business Administration
This site outlines everything in plain English. The SBA site contains a wealth of information for entrepreneurs and small business owners.