I know it's long overdue, but I recently posted some challenge labs to the site. The labs support my "Essentials of Macromedia Captivate" book.
If you'd like to try the challenge labs, go to iconlogic.com, click the Learning Center link, then the Captivate and RoboDemo link. Once there, click the projects link. This will take you directly to my Learning Management System (LMS). You can also go directly to the LMS by clicking here. There is no charge to access the Lab movies.