General 

Accessing special characters - keyboard combinations required to achieve vowel characters compounded with the appropriate accent.

Brewer's Dictionary of Phrase and Fable - browsable and searchable online version of a well-known reference book.

The Internet Pilot to Terminology - links to sites relevant to specialist terminology.

A Web of On-line Grammars

Whatis - topics and definitions of terms about information technology, especially the Internet and computers.

World Wide Words

 Acronyms and abbreviations 

Acronym Finder

Acronym Server

 Concordances 

Web Concordances - to selected poems of Shelley, Coleridge's "The Ancient Mariner", Keats' "Odes of 1819", Blake's Songs of innocence and experience, Wordsworth and Coleridge's Lyrical Ballads, Hopkins' Poems.

 Dictionaries and thesauri 

The American·British - British·American Dictionary

Dictionary, Thesaurus, Rhyming, Quotations, Anagrams, Computing Dictionaries, & Other Online Dictionaries - allows searching of numerous dictionaries and thesauri.

Phrase Finder - searchable thesaurus of English phrases, with meanings and derivations.

Scandinavian language dictionaries

The Translator's Home Companion - online dictionaries and glossaries.