http://www.tigoe.net/pcomp/index.shtml
http://www.instructables.com/
http://www.hackaday.com
http://blog.makezine.com/

Basic Stamp
http://www.parallax.com

PIC
http://www.microchip.com

PicAxe
http://www.rev-ed.co.uk/picaxe/
http://www.stepsystems.fi/tuotteet/picaxe.php (FIN)

ooPic
http://www.oopic.com/
http://www.esutech.com/OOPic/default.shtml (FIN)

Arduino (open hardware project)
http://www.arduino.cc/
check the clones as well

CATKit (open hardware project)
http://packets.goto10.org/packets/wiki/CATkit

Check also:
• Atmel microcontrollers
• Texas Instruments microcontrollers

Stores:
Bebek (FIN)
Radioduo (FIN)
Yleiselektroniikka (FIN)
Partco (FIN)
Biltema (FIN, tools)
Clas Ohlson (FIN, tools)
Maplin (UK)
Radioshack (US)

Online:
Kouluelektroniikka (FIN, check this first, nice prices, quick delivery / store in Rauma)
SP-elektroniikka (FIN, store in Oulu)
Farnell (needs account, pricey, next day delivery, massive catalogue)
ELFA
DigiKey (US, import taxes added, probably even bigger catalogue than Farnell)
Robot electronics (UK, sensors, servos etc.)
Active robots (UK, all robotics, radio, sensors, kits)
MUTR (UK, smart materials!)