If you ever spend time working on one or more billable projects and need to keep track of the time spent working on them, then Toggl might be perfect for you. Create a free Toggl account, login, and create a project. Then, whenever you start working on a project, you hit a button to start tracking the time. A clock displays the time spent. If you get called away, just hit the button to pause the clock. I find it's great for keeping track of computer support jobs.