linkFerret
Monitor your network traffic, display frames in brief, hex and detail windows, create reports, filter protocols, create link filters, and more. Filter based on protocol or link masks. Currently decodes 27 protocols now with 802.11 wireless planned.

OsMonitor Monitoring Software
OsMonitor is powerful employee monitoring software available for company. You can find out what employees are doing when they are assumed to be work in control and restrict what they should not do on computer during office hours.

LanTopolog
Provides automatic physical network topology discovery, network map visualization, detailed and searchable physical network topology map, monitoring device's state in real-time, ability to auto-discovery new devices, web browser-based access

Free IP Scanner
Free IP scanner is a very fast IP scanner and port scanner. Powered with multi-thread scan technology, it can scan hundreds computers per second. It simply pings each IP address, gets hostname, MAC address, NetBIOS information, scans ports, etc.

Alchemy Network Monitor
Alchemy Network Monitor monitors your network servers and business-critical applications availability and performance and immediately alerts you if a server gets out of order.