Until now you have seen how CI is structured and how the MVC pattern works. You have also seen how to work with databases, HTML, and forms. Looking at some of the CI helpers and libraries, you know how CI can help you in the site development process.
Now you will continue developing your application and see other great tools of CI. But first, recap what you are building—a site that will help you:
Test and keep track of your other sites
Manage them with a minimum of human intervention
Generate detailed reports of the sites and tests conducted
If possible it will run on a Cron job, in case that's not possible you can run it manually when you need or want to do it
If something goes wrong the application will send an email telling exactly what happened and where, allowing you to print those reports
With an application like that you can show the reports to your client, to impress them with the regular and comprehensive checks you are doing, and the (hopefully...