I don't know why VersionTracker segregated this application into two separate pages, one for the FREE version and one for the $30 shareware version. They're the same thing. I am going to ask them to join the pages.

Here is where you can read about the FREE version:

http://www.versiontracker.com/dyn/moreinfo/macosx/10854561

What paying $30 gets you:
1) Business and Commercial Use license
2) Dedicated 24/7 support
3) Phone support

Note that this app ONLY scans and removes Macintosh malware, NOT Windows malware. Go get ClamXav for a free option to cover both platforms.

Also note that from my perusal of their "Thread List", there is a bunch of junk on it that never/ever made it out into the wild, most of which is not even capable of self-replication. The list also includes both ye olde Mac OS malware, which is inert on Mac OS X, as well as legitimate keylogger and surveillance programs. These legitimate programs can only be installed by someone would has direct access to your computer account. Typically the only point in knowing they are installed is to ascertain whether your boss is watching you or not. And if you have to ask, also ask why you're worried about wasting your boss' time at work in the first place.

There is a similar program for Mac called 'MacScan' that has a more thorough list of detected legitimate keylogger and surveillance programs, if you want to be more thorough/paranoid. It costs $30 shareware. The folks who wrote MacScan also provide a free detection and removal tool for the "Trojan.OSX.DNSChanger" which is officially named "Trojan OSX.RSPlug.A".

BTW: At the time of my typing, Trojan OSX.RSPlug.A is the one and only verified piece of malware for Mac. It is inert on Mac OS X Server and only affects certain setups of the Mac OS X client. Reportedly there is one more recently 'discovered' Trojan horse for Mac, but its legitimacy is in question at the moment.