WatchGuard XTM - Discontinued Product - WatchGuard Technologies is strongly committed to providing industry-leading products and services.
pfSense - pfSense is a free and open source firewall and router that also features unified threat management, load balancing, multi WAN, and more
Webroot SecureAnywhere - Antivirus
ClearOS - A very good alternative for Windows Server, for free
MikroTik RouterOS - The main product of MikroTik is a Linux-based operating system known as MikroTik RouterOS.