System Nucleus is a powerful Windows diagnostic, backup, and reporting tool
One of my favorite components is the backup & recovery tool, which can process registry hives, event logs, and drivers. There's also an installed programs applet which can perform bulk actions like mass uninstalls (it's reminiscent of Safarp). Other handy items include a volume (as in drives) manager with space analyzer, startup programs and services managers, a system editor with loads of tweaking options, and quick access to virtually every Windows administration and maintenance tool via System Nucleus' tools menu.
For those who might not be quite as familiar with some of the information presented by System Nucleus, the online features are incredibly useful. They allow everything from finding out what a particular file association is all about to updating your ATI or NVIDIA drivers to running online security scans.
.Net 3.5 is required, and you can either install System Nucleus or download and extract a portable version -- both 32 and 64-bit varieties are available.