Collection of London Data Trade Directories, 17th Century Taxpayers, some volumes of the Victoria County History and much more. Material also available for other counties.
City of London Family History Research Information Useful list showing which borough a place is in is accessible by clicking on "London Generations"
Try searching the free index of Wills on "London Signatures". This site also links to The London Metropolitan Archives.
Excellent web site of the History of London's Docklands. There is a small charge for copies of entries from parish registers but there is a lot more information including churches, maps, a gallery of pictures, history of Watermen and Lightermen which is free.
East London History SocietyMore information about the East End of London including a picture gallery and further links.
The Victorian Dictionary Everything you have ever wanted to know about Victorian London