Theory: Articles on 'Electricity' - http://amasci.com/ele-edu.html  *excellent*
Introduction to Opamps - http://colomar.com/Shavano/intro_opamp2.html
Opamp Design - http://www.dself.dsl.pipex.com/ampins/webbop/opamp.htm
Elliott Sound Products "DIY Audio Articles" - http://sound.westhost.com/articles.htm
Wikipedia - http://en.wikipedia.org/wiki/Electronics
All About Circuits - http://www.allaboutcircuits.com/
Alternative Turntablism - http://forum.itchymuzik.com/index.php

Circuits:

Free Information Society - http://www.freeinfosociety.com/electronics/schemcat.php
Opamp Circuit Collection - http://www.national.com/an/AN/AN-31.pdf
All Data Sheet - http://www.alldatasheet.com
Epanorama Links - http://www.epanorama.net/links/audiocircuits.html
Red Free Circuit Designs - http://www.redcircuits.com Ken Stone's Modular Synthesizer - http://www.cgs.synth.net
John Hollis "Assorted Circuit Designs" - http://www.hollis.co.uk/john/circuits.html
Synthesizer DIY pages - http://www.uni-bonn.de/~uzs159/
LM555 Timer Circuits - http://home.cogeco.ca/~rpaisley4/LM555.html
Electronic Circuit "Beans" Collection - http://www.interq.or.jp/japan/se-inoue/e_ckt.htm
ESP Projects Pages - DIY Audio and Electronics - http://sound.westhost.com/projects.htm

Books:

The 'Thomas Henry' VCO chip cookbook - http://www.electro-music.com/forum...
An Analog Synthesizer for the 21st Century - http://www.lulu.com/content/1065518

Parts:

Dick Best - http://www.dickbest.nl/
Banzai - http://www.banzaimusic.com/
Voti - http://www.voti.nl/winkel/catalog.html
NewTone - http://www.newtone-online.nl

Bending:

Circuit-Bending - http://www.anti-theory.com/soundart/circuitbend/cb04.html
GetLoFi - http://www.getlofi.com
Wikipedia - http://en.wikipedia.org/wiki/Circuit_bending
What is Circuit Bending? - http://www.youtube.com/watch?v=w6Pbyg_kcEk

Software:

Python - http://www.python.org - the programming language for anything you can think of
Pure Data - http://crca.ucsd.edu/~msp/software.html - RT audio/video programming software
Ubuntu - http://www.ubuntu.org - out of the box linux distro
Pure Dyne - http://puredyne.goto10.org - nomad linux distribution for realtime audio/video
JAL - http://www.voti.nl/jal/n_index.html - programming language for the PICMicro Chip