There are a large number of websites that are devoted to the work of J.R.R. Tolkien. In the selection below I have tried to offer the most interesting and helpful for those who are interested in the work of this extraordinary author and scholar. The most authoritative in terms of contect (in my opinion) was the Tolkien Encyclopaedia. Regrettably this site is no longer available.
 

The J.R.R. Tolkien Information Page - a good source of web sites and organisations that deal with Tolkien and his work

The Tolkien Society - The official Tolkien Society

A Concise Listing of Tolkien Books - A helpful resource of books by and about Tolkien and his work

The Mythopoeic Society - which is an American based Society that deals with the work of the Inklings

The J.R.R. Tolkien Webrings - which will lead to to many other Tolkien websites.

Lord of the Rings Webring - which will lead to many other Lord of the Rings sites

A Tribute to J.R.R. Tolkien - a Tolkien Resource Page

The Tolkien Timeline - a biographical page

One Ring - a full site with links and interesting Tolkien material

The Tolkien Guild - with links to poems, graphics and The Tolkien Forum

The Tolkien Monster Encyclopedia - Tolkien's Monsters - catalogued for reference

The Westfarthing Tolkien Homepage - an interesting page with links to Tolkien Newgroups

The Lord of the Rings Music Album - Metrognome Studios put out a Tolkien music album, but this page has a number of useful links

The Lord of the Rings Movie Site - need I say more

The Tolkien Network - a portal to a large number of Tolkien Sites