Federal forms can be found on Search.usa.gov. Some of these include IRS forms, FEMA forms, Citizenship forms, and Business forms.
FindForms has a search engine that locates forms in various jurisdictions. Some are free, some are not. The free forms are below the pay forms.
The Internet Legal Resources Group has over 2,000 free forms available. These are not in Word format, but you can view the form and type the information into a Word document.