Here are several pieces of anti-virus/security software.
They are simply the result of a search at Version Tracker.
I have not researched any of them and cannot guarantee their performance.
MacWorld or Mac|Life magazines are good places to check for reviews.
http://www.macworld.com/
http://www.maclife.com/

If you have a MacFixIt or Version Tracker account you can check the reviews
posted there.
Otherwise I would recommend doing a Google search to look for reviews for any
product
in which you may be interested.
(Yahoo occasionally cuts off long lines. If one of the URLs below is on 2 lines
you will
probably need to cut and paste the *entire* address to your browser.)


Netbarrier
$$ - http://www.intego.com/netbarrier/

Zebra scanner 2.0.2 (Tiger compatible)
http://home.wanadoo.nl/denheyer/webpaginas/ZebraDocumentation.html

ClamXav
http://www.clamxav.com/

McAfee VirusScan® for Mac
$$ -
www.mcafee.com/us/enterprise/products/anti_virus/file_servers_desktops/virex.htm\
l

FileDefense V1.5
$$ - subrosasoft.com/OSXSoftware/index.phpmain_page=product_info&products_id=204

avast! Mac Edition and avast! Mac+PC Edition
$$ - http://www.avast.com/eng/avast-antivirus-mac-edition.html

Norton AntiVirus 11.0 for Mac
$$ - http://www.symantec.com/norton/macintosh/antivirus

AND... from MacWorld mag.

Little Snitch
$$ - www.macworld.com/article/133363/2008/05/littlesnitch2.html

Internet Cleanup 5
$$ - www.macworld.com/article/131979/2008/02/internetcleanup.html