System Monitor (Sysmon) is a Windows system service and device driver that remains resident across system reboots to monitor and log system activity to the Windows event log.
HWMonitor Portable is a straightforward hardware monitoring tool that delivers real-time statistics about the performance of your PC components. Installer version and Pro version download links are also available.
HWMonitor is a free hardware monitoring program that reads PC systems' primary health sensors: voltages, temperatures, and fan speeds. Portable version via PortableApps is also available.
PRTG - Free Network Monitor is a network monitoring solution that ensures the availability of network components while also measuring traffic and usage.
EF System Monitor gives you a well-rounded tool that can be used to retrieve a permanent record of information on all your network computers; these records include; memory space, hard disk usage, date, time, and username.
CrystalDiskInfo is an Open Source utility that monitors and displays the health of your hard drive, including basic information, S.M.A.R.T. values, and disk temperature. Also available as a portable version.
CrystalDiskInfo Portable is an Open Source utility that monitors and displays the health of your hard drive, including basic information, S.M.A.R.T. values, and disk temperature. Also available as an installer.
NetworkConnectLog is a simple utility that repeatedly scans your local area network (using ARP and Netbios protocols) and adds a new log line every time that a new computer or device connects to your network.
Wireless Network Watcher is a small freeware monitoring tool that quickly scans your wireless network and then lists all the computers and devices that are currently connected.
Libre Hardware Monitor is an Open Source fork of Open Hardware Monitor to monitor your computer's temperature sensors, fan speeds, voltages, load, and clock speeds.
DU Meter monitors your computer's network bandwidth usage with real-time graphs, along with the ability to create reports and alerts based on your downloads and uploads.