Zabbix - Track, record, alert and visualize performance and availability of IT resources
DaemonFS - DaemonFS is a real time file monitoring software.
NetVizura NetFlow Analyzer - NetFlow Analyzer is a solution for bandwidth monitoring and traffic analysis. It helps with traffic investigation, analysis and reporting
WatchDirectory - WatchDirectory monitors a file system directory and performs tasks when certain conditions are met.
Wireshark - Wireshark is a network protocol analyzer for Unix and Windows. It lets you capture and interactively browse the traffic running on a computer network.
iWatch - iWatch is a realtime filesystem monitoring program.