The Conficker Working Group is offering a simple piece of software that helps identify whether web users have been infected by the worm.
Conficker.C, also called Downadup, targets a flaw in Windows Server and despite Microsoft releasing an emergency patch and urging all web users to download it, many machines remain unprotected.
It was initially thought that the worm's creator would attempt to take control of the infected machines on April Fool's Day. While April 1 may have passed relatively quietly, the industry coalition which was formed to fight the worm still decided to release the Conficker Eye Chart.
The tool pulls images from three sites that Conficker is known to block and displays them in a box. Below the box is a guide to interpreting how you see the images - if they all show up you're in good shape, but if one or more doesn't display it could indicate a Conficker (or other malware) infection.
It's a smart and near-instantaneous test that couldn't be any easier, but keep in mind that if your computer uses a proxy server for web traffic, which can be the case in some companies, you might be infected and still be able to see the images.
See also: Microsoft warns of Conficker copycat