Cockney Rhyming Slang - An encyclopaedia article on Cockney Rhyming Slang, with examples. - http://en.wikipedia.org/wiki/Cockney_rhyming_slang
Merseytalk - Beginning with an introduction, Merseytalk provides an alphabetical and categorised listing of the rich language coined and used in Liverpool and the wider area of Merseyside. - http://www.louisville.edu/~tavan001/Merseytalk.html
A Dictionary of Slang - A searchable dictionary of over 3000 English slang terms and colloquialisms currently used in the UK, including links, word articles and a select bibliography. - http://www.peevish.co.uk/slang/
London Slang - A site dedicated to the slang of London, sometimes called 'Estuary English', including many examples of Cockney rhyming slang, a 'just heard' page and related film/books. - http://www.londonslang.com