These are some videos demonstrating some of the plugins I have developed (some of these are now a bit out of date, as the plugins have since been improved). If you want to try any of them out for yourself, you can download them form the website.

 Checklist Module
Allows teachers to create a list of items for the student to check-off. More details and download:
 Navigation Buttons Plugin
Adds next/prev buttons to each activity page in a course. More details and download:
 UploadPDF assignment type (now replaced by the PDF annotation plugin in Moodle 2.3+)
Allows for online annotation of Assignments submitted as PDFs. More details and download here:
 Realtime Quiz Activity
A quiz where every student gets a set amount of time (default 30 seconds) to answer a multiple-choice question, before the results are shown on the screen. More details and download here: