There is a wealth of related websites out there which are easy to find with modern search engines or using the comprehensive links on sites such as the Western Front Association. I won't even attempt to replicate those, but these are just a few to get you going.

OTHER WAR MEMORIAL SITES
Tadcaster WW1 Memorials	Dedicated to providing a permanent record of all those within a 9 mile radius of Tadcaster, Yorkshire, who gave their lives in the two World Wars.
Friends of War Memorials	An organisation dedicated to preserving War Memorials and their place in our communities and in our heritage.
The Jacksdale Memorial Project	A project dedicated to the people of Jacksdale in Nottinghamshire who lost their lives in the two World Wars. Part of the Jacksdale Heritage website.
The Wolverhampton War Memorials	An interesting and in-depth look at the WW1 memorials in Wolverhampton, England.
The Cullompton Memorial Project	The War Memorials of Cullompton, Devon.
The Immingham War Memorial	Dedicated to the War dead of Immingham
The Caithness Roll of Honour	The Roll of Honour for Caithness in Scotland.
"Doomed Youth"	The War Dead of the Woolwich Polytechnic 1914-1919
Leatherhead War Memorials	A Millennium Project hosted by the Friends of Leatherhead Parish Church
More Than A Name	A site developed by John Hartley which tells the stories of the men from the Stockport area who fought and died in the Great War. Includes those from Cheadle & Gatley which were the subject of John's first website, now no longer available.
"Malvern Remembers"	A site dedicated to the history of Malvern, including a Roll of Honour for both World Wars.
Cesnavicius Home Page	A site developed by Paul Cesnavicius dedicated to the men of Eccles (Manchester) and his own family members who died in WW1.
The Australian War Memorial	The website for the official Australian War Memorial.
The North-East War Memorials Project	Aims to provide a record of every War Memorial between the River Tweed and the River Tees.
GENERAL WORLD WAR ONE SITES
Trenches On The Web	The best general WW1 website I've seen.
The Long, Long Trail	An excellent site by Chris Baker. The best way to find out more is to go and visit. You won't be disappointed.
The Great War Society	A great site for anyone interested in WW1. The Society is based in America.
The Western Front Association	British based Association dedicated to the remembrance of all those who fought in WW1. Has branches in America and Europe.
Hellfire Corner	An excellent site by Tom Morgan. Includes his own material and some interesting contributions from others.
The Accrington Pals	Andrew Jackson's account of the part played by the Accrington Pals on the first day of the Battle of The Somme.
The Canadian Great War Homepage	An overview of Canada's part in the Great War
1/4th Yorkshire Regiment	A fantastic website detailing the WW1 service of Northallerton's local Territorial Battalion, taken from the Battalion War Diaries and a mixture of other sources. Also includes a full listing of all those killed whilst serving with 1/4th Yorkshires.
10th Green Howards	A record of the part played in WW1 by 10th Battalion of the Green Howards, in which my Grandfather served in 1916 & 1917.
UK GENEALOGY SITES
GENUKI Homepage	The starting point for anyone interested in genealogy relating to the UK and Ireland.
Yorkshire Genealogy	The part of the GENUKI site which deals specifically with Yorkshire. Includes a list of all civilian air raid casualties in Yorkshire in WW2.
ARCHIVE & REFERENCE SITES
The Commonwealth War Graves Commission	The excellent CWGC site now includes a searchable database of their records allowing visitors to find the location of soldiers' graves.
The UK Public Record Office	The official PRO site with lots of useful information and guides for researchers.
The Imperial War Museum	The Imperial War Museum provides a host of useful services to anyone researching Britain's part in the Wars of the 20th Century.
The National Army Museum	Homepage of the Museum of the British Army in Chelsea.
The World War One Document Archive	A very useful site containing copies of important WW1 documents listed by the year in which they were produced.
The Australian Government Archives	Can supply copies of Australian WW1 soldiers' service records and documents at a very reasonable price.... If only the British records were so complete!!!
The UK National Maritime Museum	The UK's National Museum for all things to do with Ships and the Sea.
The Liddle Collection	Peter Liddle's archive of personal accounts of those who took part in both World Wars.
OTHER SITES OF INTEREST
The Green Howards	The Website for the Green Howards Regiment. Includes information on the excellent Regimental Museum in Richmond, North Yorkshire.
Hambleton District Council	The Website for the Local Council for the Northallerton area. Includes lots of information on other tourist attractions etc. in the area.
Northallerton Web	A Website for the Northallerton area.
In Flanders Field Museum	The Website for the museum which is located in the Cloth Hall at Ypres.
WW1 Naval Combat	A site covering surface warfare between the British and German navies.
The Armourer	A militaria magazine which regularly publishes some very interesting WW1 articles.
The Plymouth Naval Base Museum	The homepage of the Plymouth Naval Base Museum and also the Devonport Dockyard and its museum.
Holts Military History Tours	Probably Britain's best known Battlefield Tour operator.
The Naval and Military Press	Book Dealer specialising in Military titles. You can order your books online at this site.
Eden Camp	An interesting museum, about an hours drive from Northallerton, which attempts to recreate the "WW2 experience".
Bovington Tank Museum	The Website for the National Tank Museum.
Wartime Memories	A site dedicated to preserving memories of WW1 and WW2 before they are lost forever.