LanFlow Net Diagrammer 

LanFlow is a drawing tool for laying out, designing, and documenting a network, LAN, internet, or other communications system.
lan net internet network wan diagram chart flow draw layout configuration design server router

MITCalc - Shaft connection 

Geometric designs and strength checks of shaped connections of shafts with hubs (keys, splines). Application supports Imperial and Metric units, is based on ANSI, ISO, DIN BS, JIS standards and support many 2D CAD systems
shaft connection shaped connection keys splines design strength check ansi b17.1 ansi b17.2 ansi b92.1 ansi b92.2m iso r773 iso 14

MITCalc - Force shaft connection 

Geometric designs and strength checks of force couplings of shafts with hubs (Interference fit, clamping connection). Application supports Imperial and Metric units and is based on ANSI, ISO, DIN BS, JIS standards.
shaft connection force couplings interference fit clamping connection ansi b4.1 iso 286 din 7190