Books, Maps, Websites - anything else that you think may be useful.

Wikipedia - London

The Open Guide to London is another wiki.

Visit London Offical tourism site.

BBC London Homepage

BBC London Weather Forecast

Yahoo Finance UK Currency Converter

Travel and Event Guides

Frommer's London

The book Frommer's London 2005 comes with a large fold-out map. You can read an excerpt: Chapter 1 (PDF). ISBN: 0764568949 Depending where you're located you can buy or get a library loan of either paper or electronic format of this book.

Lonely Planet London

Time Out London

Newspapers

The Times Online

Guardian Unlimited

Discussion Groups and Mailing Lists

Google USENET Groups - uk.local.london

Google USENET Groups - uk.local.london.info

Passes

London Pass (I don't know if this is any good.)

Language

English to American Dictionary

The American's Guide to Speaking British

BBC - h2g2 - The Origins and Common Usage of British Swear-words