A selected list of useful websites:
The Western Front Association (National)
The Commonwealth War Graves Commission
The Royal British Legion (National)
War Heritage All-Party Parliamentary Group
The London Gazette
The Long, Long Trail - The British Army of 1914-1918 - for family historians
Old Front Line Battlefields of WW1
Centre for First World War Studies
Hellfire Corner
A Guide to WW1 Battlefields and History of the First World War
British Military Nurses
National Army Museum
Imperial War Museum
The Keep Military Museum - Museum of the Dorset Regiment and Devonshire Regiment
The Wardrobe - The Rifles (Berkshire and Wiltshire) Museum
The Tank Museum - The world's best collection of tanks
War Memorials & Cemeteries
The United Kingdom National Inventory of War Memorials
The War Graves Photographic Project
Roll of Honour
War Memorials Trust
National Federation of Cemetery Friends
Family History
Dorset Family History Society
Wiltshire Family History Society
Hampshire Genealogical Society
Discussion Forums
Great War Forum
WFA Front Forum
British Medals Forum
National Archives
The National Archives - formerly the Public Records Office
Australian War Memorial
National Archives of Australia
Library and Archives Canada
SGA / Mémoire des hommes - French war dead / war diaries
CEF Study Group - Over 500 links to Great War websites
Other Western Front Association Branch Websites
A selection of other WFA branch websites:
Milton Keynes Branch
Cheltenham & Gloucester Branch
North Lancashire Branch