Macros can perform any action that you can on a web page. For example, you could use a macro to automatically submit data to a form, load a web page that you can't bookmark because it only loads once you submit form data, automatically fill in user names, and passwords or other types of forms, open multiple web pages at once in different tabs, and more.
iMacros includes example macros that demonstrate what kind of actions you can perform. You can watch them by clicking any of the "Demo-" macros in the iMacros sidebar and clicking "Play."
You can also include demo Firefox macros download files, fill forms, open tabs, take screenshots, watch slideshows, archive web pages, and more.
iOpus' official iMacros support website contains detailed user guides, tutorials, and information on scripting iMacros such as Delphi, Python, Perl and Java if you need more advanced information.
Screenshot: iMacros Firefox Extension / Chris Hoffman