[[http://www.hebeiltd.com.cn/?p=zz.led.resistor.calculator|Resistor calculator for LEDs]]

[[http://www.falstad.com/circuit/|Circuit Simulator java]]

[[http://www.wolframalpha.com/|Wolfram Alpha]]

[[http://www.csgnetwork.com/wiresizecalc.html|Wire size calc]]

[[http://www.paigewire.com/pumpWireCalc.htm|Another wire size calc]]

[[http://circuitcalculator.com/wordpress/2007/09/20/wire-parameter-calculator/|Wire calc]]

[[http://www.engineeringtoolbox.com/|Engineering Toolbox]]

[[http://www.google.com/|Google]]

[[http://www.mh-aerotools.de/airfoils/javafoil.htm|Airfoil Calculator]]

[[http://www.cncsimulator.com/index.php?page=download.htm|CNC Simulator (download)]]

[[http://www.brusselsprout.org/PCB-Routing/|PCB routing tools eagle (download)]]

[[http://hyperphysics.phy-astr.gsu.edu/hbase/emcon.html#emcon|EE Principles]]

[[http://www.eeweb.com/toolbox|EEWeb]]
====  Other  ====

[[http://www.atmel.com/dyn/resources/prod_documents/avrstudio5.0.beta.exe|AVR Studio  5 beta direct link]]

[[http://www.graphicode.com/|Gerber Viewer]]