WP Pro Quiz is a very nice plugin and give all the flexibility to make any type of questions and quizzes.
Some things need more in this..
1) Negative Marking: A quiz need to be setup for which 4 marks for each right answer but 1 marks deducted for each incorrect answer.
2) Quiz Categories: Multiple Quiz can be grouped inside categories for different competitive exams for example MAT, so that user can go inside a category and select a quiz to attempt.
3) Skip Questions: Users should be able to skip a question if he dont know answer or want to attempt it later coming back, by first attempting other questions.
4) Complete Questions attempted/missed overview, direct go to particular question (most important): A right side widget can be given which show all question number with links in the current quiz, so that clicking on a question no. direct the user to that question for attempt. It should also mention the total question existing in the current quiz and no. of questions attempted till now.
You can see the site http://pyp.co.in or http://www.previousyearpapers.com . Here you will see the grouped quizzed, click on a 'Take Test' button, when test started, you will see a right bar 'Review Questions' area showing all question no. buttons which are highlighted after each question attempted, and the skipped ones can be directly reached by clicking on a question no. button. Also its mentioning the total questions and unattended questions counts.
5) Warning before final submitting: After submitting the complete quiz there should be a message to user as a warning if he missed some questions to attempt along with counting, so that he can cancel and attempt the left ones, if time left before final submit.
6) Old results: If a registered user has given a test/quiz he should be able to view his attempted quiz details and result scores whenever he login suppose after a weak.
7) Email feature: After viewing the results user can click on a button to send the scroes to their mail id, and auto emailing can also be added.
All features mentioned above are very common in online tests and if these implemented, this plugin will be a complete online test/quiz system, which can further be used with other plugins like wp-members, user-role-editor, s2member, etc. for other payment/subscription advantage.
The site http://www.previousyearpapers.com managing these things nicely and I think the similar can be built with this plugin with just addition of these few options.
One the most important, the right widget 'review question' feature as I have mentioned in point 4 above is what I need and many users will also need.
Hope you get these things good and implement in WP Pro Quiz plugin newer release soon... :)
Please let me know what you think about these ideas..