Total Network Inventory: Professional PC audit and network inventory management software - fits best for a for companies of all sizes. Free for 60 days.
FlexiSPY - FlexiSPY is the original "phone spy" software - it's been on the market since 2005.
Network Inventory Advisor - Network Inventory Advisor audits all network software and hardware simply and efficiently
iKeyMonitor - iKeyMonitor is a mobile app for both iPhone and Android devices that with parental control capabilities and phone monitoring features.
Lansweeper - Lansweeper discovers Windows, Linux and Mac machines in your network.
MobiStealth - MobiStealth is the name of a most comprehensive smartphones monitoring application for monitoring and tracking the mobile phones of all types from an internet enabled computer.
Nmap - Nmap Free Security Scanner, Port Scanner, & Network Exploration Tool. Download open source software for Linux, Windows, UNIX, FreeBSD, etc.