Here are some links to useful dart sites on the web

Dart manufacturers
Unicorn darts Official Unicorn darts website

Double top dart shop UK based dart shop selling wide variety of dart products on-line
Harrows darts Official website of Harrows darts

Dart organisations / pro player websites
Planetdarts Official website of the Professional Darts Corporation Limited (PDC)
PDPA Official website of the professional Darts Players Association (PDPA)
WDF Official website of the World Darts Federation (WDF)
BDO Official website of the British Darts organisation (BDO)