why don't you make a task manager program, where user can make a list about his tasks, and set statuses for jobs. The start and finish date-times can filled automatically. The program then list the users who did not filled the day's task. On insert, the user should use textarea to list activities, and each rows then goes into separate events but with the selected task-type... My own task system has this feature, and evrybody love it. You can see a report on 10 AM, and check the users if somebody forget to mention a job. our managers really love it, becouse they can track the projects in type groups. This task list is unique becouse the results have to go into different output formats, in different language, and different groups.
If you need more ideas i can list here.
If you close the access till the user filled the task they don't really like this step

i'm with djjjozsi on this or if you run linux cron jobs

You can't block the user from doing anything in PHP or Javascript. You have to use a platform language like C/C++/Java/etc. I will repeat myself, you will NEVER, EVER be able to control a user's machine from the browser whether that be Javascript, or PHP, or ASP, or anything else.

but you would be able to make the server not process other data or not load certain things at certain times on the server not the end user pc which i think this is what thread is about but i could be way off

Yeah, you could make YOUR server not process their data but what this guy wants is not possible in PHP or any other language that has to do with the web (Save languages that transfer over like Java)