Weather:

Metcheck
BBC Weather
Met Office
MWIS - Mountain Weather Information Service
SAIS - Scottish Avalanche Information Service
SEPA - Scottish River Levels
Scottish Tides from BBC
Hill Phones 
The Scottish Midge Forecast

Access and Conservation:

Scottish Outdoor Access Code
John Muir Trust
National Trust for Scotland

Mountain Rescue:

Mountain Rescue Committee of Scotland
Aberdeen Mountain Rescue Team
Arrochar Mountain Rescue Team
Assynt Mountain Rescue Team
Borders Search And Rescue Unit

Clubs and Associations:

British Mountaineering Council
Mountaineering Council of Scotland
Ski Club of Great Britain
Snowboard Club UK
The Scout Association
Girlguiding UK
The Duke of Edinburgh Awards
SportScotland
English Sports Council
Sports Council Wales
Sport Northern Ireland
John Muir Trust
Visit Scotland
Enjoy England
Visit Wales
Tourism Ireland
Discover Ireland
Scottish Mountaineering Club

Holiday Companies:

Boarding Bankso
Tailor Made Trekking

Outdoor Activities:

Northern Xposure
Kushi Adventures
Scotch on the rocks guiding
Hebridean Pathways
Raasay House
Bogbain Adventure and Heritage Farm
The Ice Factor
Fort William - Outdoor Capital of the UK 

Walking Sites:

Trekking Britain
Walk Highlands

Accomodation:

UK Campsites
Scottish Camping
Youth Hostel Association
Scottish Youth Hostel Association
Irish Youth Hostel Association
Hostelling International Northern Ireland 
Love Camping 

Online Magazines:

The Great Outdoors Magazine
The Backpackers Club
Whitelines Snowboard Magazine
Fall-Line Skiing Magazine
Document Snowboard Magazine
Scotland Outdoor Magazine