Useful Links

Electronics:

http://sim.okawa-denshi.jp/en/
- a very useful website for filter calculations etc.

http://keisan.casio.com/menu/system/000000000500
- another great calculator for electronic circuits

http://www.analog.com/designtools/en/filterwizard/
- Analog Devices opamp filter calculator

http://sound.whsites.net/index2.html
- my very favorite site for audio theory and circuits, a lot of good information can be found there

AVR Programing:

http://www.engbedded.com/fusecalc
- fuse calculator

http://wormfood.net/avrbaudcalc.php/
- baud rate calculator

http://www.asciitable.com/
- ascii table