Met Police Crime Maps
Just went live in beta at maps.met.police.uk
It's a pretty decent first effort, in that the data is down to a nicely local level (typically half a dozen streets) and aggregates geographically (so you can see basic crime data for the streets near you, for your ward, for your borough and for London as a whole).
I had lots of fun working with Schulze & Webb on what an ideal crime map might entail while on secondment to the Cabinet Office. I was impressed with many of the people I met at the Met. They know crime data. They know geography.
The biggest missed opportunity is the lack of proper profile for your local coppers (aka your "Safe Neighbourhood Team"). The site should make it dead easy for your to contact them, and challenge/shape their priorities.
After all, even coppers work for you...