herdProtect Anti-Malware Scanner is a fast and free Windows desktop program which detects malicious threats, spyware and adware by utilizing 68 industry anti-malware scanners. It has no impact on your system resources and uses the herdProtect cloud-based scanning engine. The scanner is a second line of defense and is designed to work perfectly with your existing anti-virus software (we highly recommend you use another anti-malware product with herdProtect). Best of all, it's FREE.
Code:
http://www.herdprotect.com/
EDIT:
OK. The initial scan took about 90 minutes. Then it said it was checking the cloud to see if any of the files on my box were malware. It said to run a second scan after waiting 75 minutes. The second scan took about 5 minutes.
All in all, not bad for a free malware scanner. It found 6 malware files that my onboard scanner missed. Caution is recommended though because it also said some of the files I want and use were malware - false positives. But since it gives you the choice of deleting them or not, it seems like a worthwhile bit of programming. I'll probably keep it.