British Library  Reference Resources
The web site at
http://www.bl.uk/collections/wider/vrlnew.html
has direct links to a huge set of resources under the categories listed below.

Humanities Resources for Research
Virtual Reference Library

This is a listing of general reference sources available on the world
wide web, selected by British Library staff. The focus is primarily
on sources in English which have particular reference to the United
Kingdom; an indication is given if the source has worldwide coverage.
Most of the resources included are freely available on the web; any
subscription based sources included carry the information 'Onsite
access only'.

Abbreviations/acronyms Internet access
Almanacs Libraries
Archives Maps/gazetteers
Associations/organizations/societies Museums
Awards/prizes/records News
Biography Quotations
Bookselling/publishing Signs/symbols
Calendars/days/time Standards
Companies Statistics
Concordances Style guides
Conversion tools Telephone directories/postcodes
Copyright Theses/dissertations
Dictionaries/thesauri Translation tools
Encyclopedias Travel
Government Universities/colleges
Images Weather