A great addon would be one that creates: forms, surveys, polls and quizzes. This would then replace the contact form currently packaged with gpEasy. The form maker would have a contact form as one example of a form.
The form maker would have the following:
About the conditional field - condition dropdown would be: display_image, play_audio, goto_url, goto_page_anchor.
Quizzing: Quiz would have weight assign to each question, multiple choice would be randomized. Field output and field label could be formatted. Forms can be cloned.
FCKeditor 2.0 has a form toolbar. If you enable it you'll be given the option to do a lot of what you're mentioning.
There are a few other posts related to handling the form already written on the topic. I enabled the tool bar on one of my sites to create custom contact forms. Worked great!