The Victorian Web (http://www.victorianweb.org/) is full of information, and can in almost every case be strongly relied upon. The only fault I have found in it is a very thin treatment of Victorian occultism, but scholarship in this area is weak as well. The site is organized, maintained, and contributed to by professional scholars, which entails a difference of focus that some non-academics may find hard to take. Academics and the over-educated, especially historians and those interested in literature, will find this by far the most comprehensive site.
The Schoolnet Encyclopaedia of British History 1500-1980 (http://www.spartacus.schoolnet.co.uk/Britain.html) is a pretty general overview, with some very obvious gaps. It's clearly been put together for the use of schoolchildren, but it has a few gems along the way (such as the complete list of every MP from 1880-1920 with biographies).
Jack the Ripper
Casebook: Jack the Ripper (http://www.casebook.org/intro.html) is a massive archive of far more than you ever wanted to know about the Ripper murders.
Victorian London
The LSE website on Charles Booth (http://booth.lse.ac.uk/) includes a great deal more than everything you could possibly want to know about conditions for the poor in this time period. Booth also put together a color-coded map of wealth and poverty in London, which is available at the website above, browsable. The website also has Booth’s notebooks, which are fascinating by themselves, if a little tricky to read.
City of Shadows (http://cityofshadows.stegenga.net) is a nice website with lots of useful material on London and on Victorian daily life. There are lots of links as well.
The Victorian London Dictionary (http://www.victorianlondon.org/) is really exceptionally good, but to some degree you have to know what you’re looking for.
Links Etc.
“Exquisite Victorian Links” (http://www.gfy.ku.dk/~ams/sh/victorian.html), from a Sherlockian website, has a great many useful links; the rest of the site is decent.
The Victorian Literary Studies Archive from the University of Nagoya, Japan, (http://lang.nagoya-u.ac.jp/~matsuoka/Victorian.html#Victorian), has a huge number of links and some useful information.
The Victorian Prose Archive (http://www.victorianprose.org/), in addition to having a certain number of e-texts, has a really vast list of links with descriptions.
-- ChrisLehrich? - 22 Dec 2004