Anti Flashback Trojan is a free application that checks for the Flashback Trojan.
Flashback is a variant of the Tsunami Trojan for Mac OS X, and has so far infected over 600, 000 of them. Now you can check whether your Mac is infected with the Flashback-Trojan without resorting to manual removal in Terminal. For more information what Flashback does, including manual removal instructions, see the F-Secure website.
Incidentally, all my apps are free, so any donation would be very much appreciated.