Why anti-virus scanner for Linux?
You are right about Linux having few viruses. I believe there are around 40 known Linux viruses in general, and 3 are in the wild (when this FAQ was written). However, Linux has become a ever more popular choice as a server operating system, and it has begun replacing many Windows Servers as mail servers and file servers (samba). This is one of the reasons for having a virus-scanner for Linux, to be able to detect/disinfect incoming e-mail, or to prevent people from downloading infected files through samba (samba-vscan + Enterprise version of F-Prot Antivirus for Linux).