James Cheshire (Department of Geography, UCL) produced a series of interactive maps of London that show the relationship of common surnames to different neighbourhoods:
This map shows the 15 most frequent surnames in each Middle Super Output Area (MSOA) across Greater London. The colours represent the origin of the surname (*not necessarily* the person) derived from UCL's Onomap Classification tool. The surnames have also been scaled by their total frequency in each MSOA.
(via Sociological Images)