Reason Core Security is a tool for detecting, removing, and generally protecting you from malware, adware and similar unwanted programs.
The free version doesn't have real-time protection, and is no substitute for a full-strength antivirus. But you can scan files or your entire system on demand, check your installed programs for risks and fully uninstall them (including cleaning up after the original uninstaller), and manage your startup programs and all your browser addons from one place.
One unusual feature is "bundle protection", a module which monitors program installations, looks for attempts to install adware, and automatically unchecks those checkboxes for you (technology bought in when Reason acquired the rights to use Unchecky).
There's also a "Remediation" module which can reset various areas of Windows to repair any system damage or corruption (network settings, proxies, system policies, Explorer settings, IE home page and search providers, more),
Upgrading to the commercial version - priced from $29.99/ year - gets you real-time protection and scheduled scanning, too.
Reason Core Security has one or two useful extras, but its scanning was horribly slow on our test system, and its recommendations weren't good ("Norton Security Toolbar" and the popular Chrome extension "Pushbullet" were both tagged as risky). Much more work required.