There's been a huge amount of interest on Twitter and in the media about the new Bomb Sight website, developed by the University of Portsmouth with assistance from the National Archives and elsewhere, and deservedly so because it's fairly excellent. In short it's an interactive map of the London Blitz compiled from a number of sources, showing where what kinds of bombs fell when. So you can browse to (or search for, though this has been temporarily disabled due to high traffic) your favourite part of London and see why there's a mid-20th century building interrupting that otherwise Victorian facade. Zooming in you see a marker for each bomb fall, with a link for more information. You can also get a statistical overview for each borough or ward, or for Greater London as a whole. Each location links in with relevant Blitz photographs sourced from the IWM, as well as related stories from the BBC's WW2 People's War site. In the map view, you can flip between the aggregate bomb census over seven months, or a single week's worth of bomb falls, or just the first twenty-four hours. You can also overlay the original Home Security maps from which the census data is derived, which is valuable because, thanks largely to the Blitz itself, some streets which existed in 1940-1 can no longer be found. As a bonus, London's invasion defences can also be displayed, using data taken from the Council for British Archaeology's Defence of Britain Dataset. An AR app is on its way, though sadly only for Android devices, not iOS.
Despite popular impressions, Bomb Sight doesn't show all the bombs recorded falling on London during the Blitz, but only those recorded between 7 October 1940 and 6 June 1941 as well as those recorded on 7 September 1940. That is, nearly the first month of the Blitz is missing. (This is quite clearly stated but it would be easy to overlook.) The reason for this is that the weekly bomb census maps only began to be compiled a month into the Blitz. It might be possible to fill in the gap from other sources; that's what has been done with the first day of the Blitz, which is from London Fire Brigade records via the Guardian. Of course, coming from different sources the data will be disjointed but that is inevitable with this kind of project. I gather that it is also intended that all the weekly censuses between October and June will be added to the site, which would mean you could slide through the weeks to see how the bombardment changed over time; or else further research might pin down the date of each bomb (at the moment when you click on one it only gives the census period, i.e. up to an eight month period). It would also be extremely interesting to compare bomb falls from the First World War, if only to illustrate the differences in the scale of bombing.
Also, Bomb Sight only covers London. Again, this is at least partly due to the nature of the data sources. But again it's something which could be remedied. Other, smaller Blitz maps like this have already been done for Southampton and for the West Riding of Yorkshire (for the night of 14 March 1941; from after the Blitz there is also Londonist's V-2 map. Depending on the permissions and formats, and hand waving wildly, it should be possible to aggregate these maps into Bomb Sight, if desired. Or else somebody else could build a website to do the aggregation. But in the end, somebody would probably have to do the hard work of sifting through local ARP records to generate the data for outside London, assuming those records do exist and are detailed enough.
None of which is intended to cavil at what the Bomb Sight project has achieved, as it's very good stuff indeed.