Looking up forms for customers is something librarians in public libraries do quite often and I am sure that the new government portal Forms.gov, designed to make this process much easier is going to be appreciated a lot.
Forms.gov "provides citizens and businesses with the ability to search for business and citizen federal forms needed to interact with the Federal Government."
Customers can search forms by keyword, alphabetically A-Z, alphabetically by owning government agency and by agency
Although the site holds over 5,400 business forms, not all forms from government agencies are available. If you are not able to find what you are looking for, try www.usa.gov or do a general search to locate which government agency publishes your form and look it up on their page.