Online virus checker for free

NoVirusThanks.org offer a free service that scan suspicious files for possible presence of virus, worms, trojans and any other kind of malware using several Anti-Virus engines.

Features:
- Free and independent service
- Use of multiple antivirus engines
- Automatic updates of virus signatures every 6 hours
- Detailed results from each antivirus engine
- Advanced details of file analyzed
- BBCode support

kaspersky

If you discover a suspicious file on your machine, or suspect that a program you downloaded from the Internet might be malicious, you can check the files here.Indicate the file to be checked; it will automatically be uploaded from your computer to a dedicated server, where it will be scanned using Kaspersky Anti-Virus. Multiple independent tests and publications acknowledge the solution to have exceptional detection rates. Updates every three hours ensure that even the very newest viruses can be detected.

Only one file of up to 1 MB can be checked at any one time. If the file is too large, a window with an error message will be displayed. Type the name of the file in the window at the top of this page, or find the file using 'Browse'. Then click on 'Submit'.If you have several potentially suspicious files, you can check them one after the other, or create an archive file (in zip, arj or similar format) and check that. The archive should not be larger than 1 MB

Some other free scanners available online
http://www.bitdefender.com/scan8/ie.html

leading anti-virus vendors McAfee Inc. and Symantec Corp. have rich online scanning tools, but these services do not actually remove detected threats.