Generic help:

PID controller from wikipedia.
The IR-sensor used in the pipe setup: GD2D12

Atmel AVR microcontrollers:

AVR-freaks. Everything about ATmel AVR microcontrollers (specs, tools, code samples, links...)
Atmel's AVR web site Software (Atmel studio, AVR GNU compiler etc.) and datasheets.

IC manufacturers:

Maxim IC / Dallas semiconductor
Texas instruments
National semiconductor
Philips semiconductor
Atmel
ST microelectronics

IC distributors:

Digikey Finland   source for component orders on this course
Farnell
Elfa

IC shops:

SP-elektroniikka  
Suomen huoltopalvelu (Oulussa)
Bebek
PartCo
El-kama
Elektrolinna