Track How You Spend Your Time Online With RescueTime

RescueTime is a web-based time management tool that keeps track of what you do and for how long when you are on your computer.
The Y-Combinator discovery just raised another $900,000 from True Ventures, Chris Sacca, Tim Ferriss (4-Hour Workweek author), Mike Seckler and Mike Koss.
The site has 100,000 users and is growing 5% a week claims investors.

How will they monetize and will you use this tool?