Check this one out..

http://virusscan.jotti.dhs.org/

Jotti has set up an online scanner that scans suspicious files with multiple scan engines.
He has just recently added avast! and mks_vir (and reset the stats to be fair)

No ActiveX required, just a browser with JavaScript.

If something new is found, it will be submitted to the various AV companies.

Currently it's scanning with Antivir, avast! , bitsdefender, clamav, f-secure, kaspersky and mks_vir.

typically, it might take up to 45 seconds to scan a file but that's not too bad considering all the engines it's using.. And the fact that the server isn't the fastest around but hell, I think this link is a keeper..

enjoy..