We've divided the links up into sections depending on the amount of linguistic knowledge required to understand them. Each link has a description of what it contains.
…requires very little to no linguistic knowledge, like this website.
Online Tengwar Trabscriber
This website can transcribe Elvish text into Tengwar, the Elvish writing system.
Glǽmscrafu - Tolkien's Linguistic Cellar
A list of Tolkien's compositions in other languages, translated and with audio files of people reading them out loud.
Merin Essi ar Quenteli!
This website is designed to fit the linguistic needs of fanfiction writers and RPers. It has thousands of names and phrases listed, (mostly in Sindarin and Quenya).
Mellonath Daeron's Elvish Phrasebook
The phrases are small in number, but have aged remarkably well. They didn't step very far beyond what was known of Elven languages at the time it was written.
Quenya Lapseparma - Quenya Babybook
Careful translations of hundreds of common English names into Quenya!
Now We've All Got Elvish Names
An article on Ardalambion. It's fairly short, but very well done.
The Council of Elrond's Elvish Names Database
It is HUGE, and the efforts of a group of people working together. The rest of COE's Elvish section is a bit outdated, but this section has aged quite well.
…requires a little linguistic knowledge, but is still understandable by the layman.
Comprehensive analyses of the various Elven writing systems.
Dan Smith's Fantasy Fonts for Windows
Analyses of Elven writing systems, and lots of fonts!
Elvish Pronunciation Guide
Despite its name, it's only for Quenya.
Your Sindarin Textbook
An off-shoot of "Merin Essi ar Quenteli!", it's a combination textbook and online class, where you can interact with the person who wrote the textbook, turn in homework, and get it corrected.
Ardalambion's Quenya Course
It's a textbook for people who want to learn Quenya, but aren't linguists and find the technical analyses difficult to understand.
Parma Tyelpelassiva's Textbooks
One in Sindarin, one in Quenya, and one in Adûnaic.
Hiswelókë's Online Dictionaries
The best Sindarin dictionary on the web. It's missing most of the entries from Parma Eldalamberon 17, but it's still incredibly useful, being the only such dictionary that includes careful page references for each word.
Ardalambion's Quenya Wordlists
The best Quenya dictionary on the web.
Parf Edhellen ~ Parma Eldiéva ~ Elvish Book
A massive database of all of the words in Hiswelókë's Online Sindarin dictionary and Ardalambion's Quenya Wordlists.
…means that these websites' contents are highly technical and difficult to understand if you've never studied Linguistics.
Ardalambion - Land of Languages
This website contains careful linguistic analyses of most of the languages that Tolkien made up - even a few that he made up as a child! Some sections have been outdated by recent publications, but this website remains as one of the best sources for Tolkien-language enthusiasts.
Parma Tyelpelassiva - Book of Silver Leaves
A small mountain of linguistic articles analyzing a handfull of Tolkien's more complete languages, and at various stages of their development.
A bit of gap-filler, studying little bits and pieces of Tolkien's langauges that are oft' ignored. It also has a section on Glossopoeia, or constructed languages.
I Lam Arth - The Noble Tongue
A collection of linguistic articles about Sindarin.
A group of Tolkien-language enthusaists and the articles and compositions they've made.
Gwaith-i-Phethdain - Fellowship of the Wordsmiths and G-i-P Report
Lists of linguistic essays and compositions in various languages created by Tolkien. The Report is an analysis of the language use in The Hobbit movies as they come out.
The Elvish Linguistic Fellowship (E.L.F.)
The place where you can find the latest publications of Tolkien's notes and translations.
Home and storefront of another set of publications of Tolkien's notes and translations: Parma Eldalamberon.
A community set up by David Salo to encourage the linguistic investigation of Tolkien's languages.
A mailing list (remember those? probably don't… it's an ancient form of internet forum) devoted to Tolkien's languages. Still very useful, allbeit confusing for we savvy internet youths.