EXPIRED - MacScan for free - today only (20th September USA time). Note that you must download, install and register today using the 'PIRATE' coupon!
OK, so you probably don't need this software on your Mac, but it doesn't hurt to scan for baddies so you don't pass them on to your Windows friends…
hmm…i can't get it working
edit: expired, 5pm our time is midnight, so it's 21th over in USA as well.