Dive Organisations

• PADI
• BSAC
• Technical Diving International (TDI) - Also links to their sister organisation SDI for less technical diving
• Sub Aqua Association (SAA)
• Scuba Schools International (SSI)
• Global Underwater Explorers (GUE) - want to know what all this 'Doing it Right' stuff is about
• Divers Alert Network (DAN) - European site
• The British Diving Safety Group - including Advice Regarding DSMBs

Dive Magaizines

• DIVER - still one of the best magazines on the shelf
• DIVE - BSAC's official magazine.
• DiveGirl - Dedicated to you girls out there, but some great articles
• SportDiver - PADI's official magazine
• immersed - International Technical Diving magazine

UK Diving

• UK Diving - major source of info for UK divers
• UK Divers.net - another great site for diving in the UK
• UK Divers.com - Networking UK Divers
• UK Scuba - lots of links & info
• UKRS - uk.rec.scuba forums

Equipment Manufacturers

• AP Valves 
• Apeks
• Aqua Lung
• Custom Divers
• Dive Rite
• Extreme Exposure
• Northern Diver
• GreenForce
• Hartenberger
• O'Three
• Oceanic UK
• OMS
• Polar Bears
• ScubaPro
• Sea & Sea
• Suunto
• Weezle

Misc. Sites

• DDRC - Diving Diseases Research Centre
• RNLI - The Diver's best friend!
• RAC Route Planner
• AA Route Planner
• Multimap - maps, directions & loads more info (Not just the UK)
• Streetmap - better maps than Multimap but can be a bit slow