Hi d33muli,
My name is Milen Velikov from Bulgaria, and I’m drupal developer with 2 years’ experience on drupal custom module development and theming. I have strong knowledge of drupal hook system, and work with User API, Form API, Field API, Database abstraction layer, Action and triggers (this part is that you need), Schema API and more. Work perfectly with some fundamentals modules like Views.
About your specific project’s module, I have the next points:
First of all, you must to now that, to track to user’s time spending on the site, we need a script that regularly( every sec, every minute, every 2 minutes or every your needs) will hit your server, and this will increase your server load. There is a lot of solutions, but the difference between them is the performance. I can say that I have the right solution.
My solution will be in a mode drupal module, who you can install on every drupal 7 installation.
If you need, I can do( for extra pay), the configuration page where site admin can choose an options where the track script must be run, like by content type, by user role, by datetime or something others options.
This is the base outline.
Regards, and sorry for my poor English,
Milen Velikov