Slife is an activity browser for MacOS X. When the Slife client runs, it observes as you interact with applications, documents and web sites in your computer. It keeps track of when and for how long you work on projects, read news, check email, etc.
Slife offers several visualizations that makes it easy to identify when you work and what you do in your computer. You can create "Activities" to categorize your computer tasks and even set goals for yourself (i.e. "spend only 20 minutes a day watching online videos").
Please note that while the Slife source code is available here under the GPL license, it relies partially on code snippets from other authors, under other licenses.