FreeMeter - Monitor network bandwidth (C#.NET 2k/XP+). Desktop and Systray graph.
GlassWire - Visualize network activity in detail, get notified when new apps access the network, look out for...
Network Lights - Network Lights is a Windows program, which blinks keyboard LEDs (Light Emitting Diode) indicating outgoing and incoming network packets on network interface.
TinyWall - Lightweight and non-intrusive firewall
TrafficMonitor - TrafficMonitor is a network monitoring suspension window software in Windows.
Little Snitch - Little Snitch is a firewall application that monitors and controls outbound internet traffic.