Drawing Circuits

Xcircuit : An open source software for drawing circuits. The stencils or libraries as they are called are available for every possible schematic component that you can imagine. The only down side for some can be that it is a Linux/Unix based tool and you may need to install cygwin for running it on a Windows machine. Click here to goto Xcircuit's tutorial page.
Dia : A Windows/Linux based software for drawing schematics/circuits etc. The software is free and is distributed under the GPL license.
MS Visio : An expensive tool from Microsoft for drawing all kinds of drawings. Apart from the cost of the software the biggest disappointment is that it has no eps/ ps support that is a necessity when writing papers in Latex.