What antivirus program do you use?

I used to use several when I used Windows as my operating system, but now I use none as a Linux user. It's still possible to get a computer virus using Linux, it's just that it's much less likely. There are no hidden back-doors that allow sneaky reporting and exploitation of vital system files like Windows has, and one needs to give any program express permission to install with your personal password. Many Linux software programs are available as open source, so one can read and compile them yourself...and even if this kind of thing was not for the average user, Linux installation of software is often linked to a repository of software that has been tested for malware and is known to be safe.

I really don't miss the headaches that came with Windows viruses and anti-virus software (real and bogus) that I had to install/pay for when I was a Windows user.