Open Hardware Monitor - Monitors temperature sensors, fan speeds, voltages, load and clock speeds, with optional graph.
Total Network Inventory - Total Network Inventory is a piece of software designed to help with managing software inventory and auditing PC systems.
SpeedFan - Hardware monitor for Windows that can access digital temperature sensors located on several 2-wire SMBus Serial Bus. Can access voltages and fan speeds and control fan speeds. Includes technical articles and docs.
Lansweeper - Lansweeper discovers Windows, Linux and Mac machines in your network.
Speccy - Speccy - find the details of your computer's specs. Great for spotting issues or finding compatible upgrades. Download the latest version free.
Spiceworks Help Desk - Help desk software features that work for IT