Nmap - Nmap Free Security Scanner, Port Scanner, & Network Exploration Tool. Download open source software for Linux, Windows, UNIX, FreeBSD, etc.
HWiNFO - Professional System Information and Diagnostics. Comprehensive Hardware Analysis, Monitoring and Reporting for Windows and DOS. FREEWARE. download. Advertisements.
Fing - Discover which devices are connected to any Wi-Fi network, map devices, detect intruders, assess...
Neofetch - Fancier version of Screenfetch that displays colors and supports more platforms.
Advanced IP Scanner - Advanced IP Scanner shows all network devices, gives you access to shared folders, and can even remotely switch computers off. Download it Free.
Speccy - Speccy - find the details of your computer's specs. Great for spotting issues or finding compatible upgrades. Download the latest version free.