Malware scanner for Mac

One of the things I like about Linux is that I no longer have to spend a lot of time (in fact, NO time in Linux at all) doing spyware and virus scans or defragging.
Indeed, Although I rarely use OSX at all, I have never in the 10 months I've had it, done any malware scanning in OSX either.
Nevertheless, here's a malware scanner for Mac that might be useful to have lying around. Sounds like something that might be useful to dust-off once a year or so.