Free (released under the GNU General Public License) disk defragment and optimize utility for Windows 2000/2003/XP/Vista/X64. Completely automatic and very easy to use, fast, low overhead, with two optimization strategies, and can handle floppies and USB disks/sticks. Included are a Windows version, a commandline version (for scheduling by the task scheduler or for use from administrator scripts), a screensaver version, a DLL library (for use from programming languages), and versions for Windows X64.
Aaah.. here are all the tools from the most outstanding IT company in the world! "ThoughtWorks has a very high concentration of open source developers in its ranks. Here you can find a comprehensive resource of ThoughtWorkers' contribution to open source.
M. Godfrey, and Q. Tu. Proceedings of the International Conference on Software Maintenance, page 131--142. Los Alamitos, California, IEEE Press, (2000)