I recently started a telecommuting job that requires me to log my hours to different projects. I started out using Stopwatch and logging time on a spreadsheet. One drawback of Stopwatch is that it seems to be a bit resource hungry. Not needing millisecond accuracy, I decided to look for something else. Enter the Hamster time tracking applet for Gnome. This is a panel applet for the Gnome desktop environment. If you're using something else as your desktop then you're probably out of luck on this one.
First off; how to install it. I'm going to show you how to install it on Ubuntu 8.04 (Hardy Heron). You'll need to add the package sources to your /etc/apt/sources.list file. You can do this by editing the file as root or you can go through the Ubuntu menus. To use the menus go to System -> Administration -> Software Sources. Enter your password at the prompt. Select the Third-Party Software tab and click on Add. Add the following line into the APT line section and click on Add Source.
Now just click Close on the Software Sources dialog and click Reload when the prompt comes up. Once the package sources are reloaded we're ready to install Hamster. Open a terminal and type:
Make sure to say yes when asked to install the package without verification.
You can now add Hamster to your Gnome panel by right clicking on the panel and selecting Add to Panel. Scroll down the list and select Time Tracker and click Add. You should now see an applet that says No Activity on it. Right click on it and select Preferences. From this menu you can add new categories and activities. To delete something, just select it and hit Delete on your keyboard.
Have fun! To learn more about Hamster you can visit the Project Hamster homepage.