Grindstone is a freeware productivity tool which tracks the time you spend completing tasks on your computer in order to help you become more efficient and productive. We’ve covered this type of thing before with the RescueTime product, but where this program differs is in extensibility and also the practicality of the data.
For instance, Grindstone contains both timesheet and invoicing modules, which makes it a very practical tool for freelancers and others who charge by the hour. In some ways, therefore, the software can also be used to manage tasks rather than just monitor, which is somewhat akin to a To-Do list on steroids.
If you’re into identifying the strengths and weaknesses in your working day, this has got to be a great place to start, and with the addition of the online component – called TaskForce – it’s an even better tool for that purpose. Not sure about the name though, guys. 
Grindstone greatly simplifies everything about staying on top of your time, from automatically recording it to producing useful reports based on it. Just tell Grindstone what you’re working on and it will keep tabs on your time in the background while you work. Incorporating automatic away detection, advanced task and time management functions, and customizable billing calculation, Grindstone is the most powerful personal time tracking solution, period.
Aaaaaaggghhhhh!!!
Please, please, please let us know if a piece of software is Windows, Mac, Linux, or cross platform. REALLY irritating to have a review to find at the site itself that something is windows only.