I finally worked out how to use GMapCreator well enough to create a few maps (not interactive, yet) of the Neighbourhood Statistics data.
These show the distribution of people in each age bracket (yellow = high, red = low) across London wards.
I think the images demonstrate that 20-40-year-olds live in different parts of the city from 40-60-year-olds (at least in 2001, when the census data was collected).
0-20:
20-40:
40-60:
60-80:
80-100:
