ClamXav
MacDevCenter recently featured an article about ClamXav, a free virus scanner for Mac OS X. ClamXav is based on the open-source, antivirus engine ClamAV. With the loss of Virex as an incentive for purchasing .Mac, François Joseph de Kermadec's article convinced me to download ClamXav and give it a whirl. I now have it configured to automatically scan my home account every night at 3 AM, after it checks for the latest updates. It also will scan, in the background, any file that ends up in my downloads folder. The app is Java-based, so it's a little slower than I'd like on my 1 GHz PowerBook, but hey, it's free. It does appear to be put together well, otherwise. We have very few virii to worry about on the Macintosh side of the fence, but it never hurts to be prepared.