Windows: If you track how you spend your time, sometimes the tracking is more tedious than the doing. Free app TimeSheet automatically logs your tasks based on user-defined rules, so you can spend more time working and less time managing.
Detailed time logging is popular in fields like law and public relations, where projects must be billed to certain clients — but a program like TimeSheet can be useful for just about anyone looking to see specifics on how they're spending their time. TimeSheet allows you to create rules that will assign specific applications (or even more specific, window titles) to a project and/or task within that project. As you move in and out of those windows, TimeSheet will log how much time you're spending on those particular tasks and projects — which can help you bill the clients of those projects or just help you keep an eye on your productivity. You can also add time manually if necessary. When you're done, TimeSheet provides a nice report of the time spent on any given task, which you can import into Excel and send along if need be (or file away for reference later on).
TimeSheet is a free download, Windows only.