Thanks for ghacks.net for pointing me towards GnoTime, a time-tracking tool for independents, freelancers or just about anybody that needs to keep track of time when working on billable projects. GnoTime can keep track of time spent on projects. It shows flexibility with support for multiple rates. When you are ready, you can print out an invoice that can be sent to clients. GnoTime is already in the Ubuntu repositories. All you have to do is install: sudo apt-get install gnotime. Give it a try.