MyDefrag: The disk defragmenter formerly known as JkDefrag
MyDefrag actually offers a handful of different tools, that let you perform actions including analyzing your disks, defragmenting, or optimizing them. The program is faster and more customizable than the built-in Windows defrag utility. And it offers a ton of statistics as it defragments, along with a rather busy looking visualization. You can zoom in on the visualization by clicking on the screen, though.
While the software was based on JkDefrag, MyDefrag includes a new set of command line parameters and is no longer compatible with older versions of JkDefrag. You can find a complete list of changes by reading the release notes of MyDefrag 4.0 as well as the 12 beta versions that preceded it.