The following are some resources that you might find helpful
AVServiceCloud.com – Track AV Maintenance Contracts from a web based interface
iTestGenPRO – AV Test generator for iPhone/iPad: HDMI, VGA output of test patterns and audio
Google Sketchup – Full Featured 3D drawing program. Free download.
Extron DataViewer - Handly little (free) tool to check communication to/from serial and ethernet devices.
PuTTY – Free SSH/Telnet/RS232 communication tool – great for diagnostics.
Ammyy Admin – Low Cost (free trial, with a free version) Remote Desktop control software: Great for onsite support of field technicians.