Malwarebytes - Malwarebytes protects you against malware, ransomware, and other advanced online threats that have made antivirus obsolete and ineffective. Free Anti-Malware & Malware .
Panda Antivirus for Mac - A bare bones malware and anti-virus scanner.
Avira - Cloud based email security solution
Clam Xav (desktop) - Specifically with Clam Xav Sentry configured to scan inserted disks.Please read global comments on this question for an explanation of why desktop apps are being recommended for virus detection on ios devices.
Easy PC Optimizer - Easy PC Optimizer is an easy and quite simple tool for enhancing the performance and boosting up the speed of the system.
Microsoft Security Essentials - Microsoft Security Essentials is Microsoft's own foray into the world of virus protection.