You can use it as:

• usual form features:
  • contact form
  • sendcopy implementation
  • works with J! captcha plugins
  • major survey jumping from one form to the next
  • store all data in database via J! messages component
• developement features
  • custom validation class
  • custom preprocessing of data
  • custom functionality via predefined class
• paid version
  • fill database table
  • send/store files

Validation both via Javascript and PHP via Joomla! Data is sent via email to a contact email address. Also possible is cascading the forms, so that you can generate a major survey jumping from one form to the next. There are many more features (e. g. use captcha plugins and prepared class to do "something else", means to add your own code), see yourself:-)

As knowledge about xml formatting and Joomla! form generation is needed, mod_qlform is a useful and mighty tool for developers.

All form fields see here: http://docs.joomla.org/Category:Standardformfield_types