McAfee Security Scan Plus is a free diagnostic tool that ensures you are protected by actively checking your computer for up-to-date anti-virus, firewall, and web security software so you always know if your computer is safe.  It scans for threats such as malware, Trojans, and unwanted programs actively running on your computer. It even scans your browser history for suspicious activity. McAfee Security Scan Plus scans your computer in under two minutes, never slowing down your work or play. In addition, you can customize how often you want your computer scanned. When a scan is complete, you’ll see the status of your security protection. If problems are detected, McAfee will provide security solution recommendations.

HouseCall is Trend Micro's highly popular on-demand antivirus software scanner for identifying and removing viruses, trojans, worms, unwanted browser plugins, and other malicious software.

Bitdefender QuickScan uses in-the-cloud scanning technology to detect active malware on your system, in under a minute. Because it focuses on active e-threats, the product uses just a fraction of the system resources needed by a regular virus scan and requires no time-consuming virus signature updates, as the detection process is performed by remote Bitdefender servers.

Detect and remove malware on your PC with a powerful and user-friendly tool that uses the same ThreatSense® scanning technology and signatures as ESET Smart Security and ESET NOD32 Antivirus — just by using your web browser.

Panda Cloud Cleaner is an advanced disinfector based on Collective Intelligence (scanning in-the-cloud) that detects malware that traditional security solutions cannot detect.

Kaspersky Security Scan provides a free-of-charge, easy way to find viruses and other threats that may be hidden on your PC… plus get advice on your PC’s security status.

Symantec Security Check tests your computer's exposure to a wide range of online threats. It's free and an effective tool that helps determine your Internet security needs.