Below are a collection of useful files for computer repair and maintenance.
CCleaner - Removes unnecessary files and registry info
JkDefragGUI - reorganizes files on your PC to improve performance.
DriveimageXML - backup your entire PC contents
Explore2fs - access files on Unix partitions
Double Killer - remove duplicate files
Deep Burner - backup information to a CD or DVD
7-Zip Portable - create and extract from popular archive file formats
PC-Decrapifier - uninstalls common trialware
Information
Process Explorer - Task Manager Replacement (more powerful)
System Information - System Information Details
ProduKey - Product ID and CD Key Finder
Autoruns - Identify programs started by Windows at boot time or when you log in.
HWMonitor - Temperature Monitor
GPU-Z - Identify the graphics component of your PC.
WirelessKeyView - Retrieves previously used wireless network keys/passwords stored in your computer,
TreeSize Free - View the amount of disk space used by any folder on your PC.
Game Key Revealer - Retrieves the CD-Key and serial numbers for all installed games on your computer
USBDView - Allows you to review the software installed to manage hardware connected to USB ports.
TrID - Determine the type of file (Word, Excel, PDF) when Windows can't because of different ext.
Codec Installer - Displays the video codecs currently installed on your PC.
Unknown Devices - Helps you identify unknown devices
GSpot - Analyzes video files to determine the video and audio codecs required
Repair Tools
Norton Removal Tool - Lets you easily remove specific Symantec products.
McAfee Removal Tool - Lets you easily remove McAfee consumer products.
LSPFix - Restores Internet access caused by faulty Layered Service Provider software.
Dial-a-Fix - Advanced utility for 32-bit versions of Microsoft Windows fixing common problems easily.
Recovery
Recuva - Recovers files which have been deleted from your computer
Restoration - Recovers files which have been deleted from your PC
Photorec - Recovers files even if your media's filesystem has been severely damaged or re-formatted.
DBXTract - Recovers e-mails from damaged Microsoft Outlook Express data files.
Network Tools
Wireshark - Allows network packets to be viewed and helps diagnose network problems.
Network Scanner - Lists which type of resources are available on the network.
PuTTY - SSH and Telnet client that allows you to login to Unix computers or devices
Network Stumbler - Wireless network scanner that lets you see network availability and signal strength.
Virus and Malware Removal Tools
ClamWin Antivirus - Virus Scanner
Rootkit Revealer - Rootkit detection utility
Combofix - Manual removal of spyware infections.
SmitFraudFix - Command prompt tool which removes "Desktop Hijack malware."
RogueFix - Detects and cleans Windows XP computers that are infected with fake security warnings
HijackThis - Scans your computer to find settings that may have been changed by spyware
HijackReader - Reads the log files create by HijackThis and provides advice on what to do.
SUPERAntiSpyware - Detect and remove spyware
Malwarebytes - Search and destroy malware
Miscellaneous
Mozilla Firefox Portable Web browser - Standalone application
JavaRa - Removes old and redundant versions of the Java Runtime Environment (JRE).
Monitor Tester - Helps you adjust the settings of your monitor to get the best picture.
Dead Pixel Tester - Find any pixels on your LCD screen which are "stuck" or "dead"
ChkFlsh - Checks any flash drive for errors and displays their actual capacity.
Double Driver - Allows the device drivers that came with your PC when you bought it to be backed up.
SumatraPDF - Allows PDF documents to be viewed without having to reinstall Adobe Acrobat Reader.
Revo Uninstaller - Helps you easily remove unwanted programs installed on your computer
Tweaks
TweakUI - Lets you change various settings that are not exposed in the default user interface.
VistaTweaker - Tweaking utility designed for Windows Vista