x11vnc allows one to remotely view and interact with real X displays (i.e. a display corresponding to a physical monitor, keyboard, and mouse) with any VNC viewer. It is designed to be compatible with all Unix variants and Mac OS X, and depends on a small set of standard libraries. It supports SSL/TLS and VeNCrypt encryption, Unix password logins, single port access, Zeroconf, file transfer, and UltraVNC extensions. It is part of the LibVNCServer project.
PortSensor is a powerful Windows/Unix server monitoring tool with Linux/Mac/Windows clients. Sensors can be created to monitor nearly any TCP/UDP service, such as: HTTP, FTP, POP3, SMTP, MySQL, and DNS. Custom sensors can be created to monitor your other critical server metrics, such as processor loads, mail queue loads, disk space usage, and log activity.