Panda Security - 16.5 MB - Trial
Fast and free, boasts the top score in real-world protection!
Sophos Ltd. - 157.36 MB - Freeware
Protect your Mac from Viruses, Trojans and Worms
Trend Micro Inc - 66.3 MB - Trial
Full protect your Mac against viruses and other malware
Intego - 28.5 MB - Trial
Macs Need Antivirus Protection Software, Just Like Any Other Computer!