http://www.symantec.com/securitycheck
http://www.bitdefender.com/scan/licence.php
http://housecall.trendmicro.com/housecall/start_corp.asp
http://www.trendmicro.com/spyware-scan
http://support.f-secure.com/enu/home/ols.shtml
http://www.ewido.net/en/onlinescan
http://www.kaspersky.com/virusscanner
http://www.pandasoftware.com/products/activescan.htm