I have loaded the CodePoint Open data into a database some time ago. It was released as part of the OpenData from Ordnance Survey, though it is Royal Mail data originally. As part of the bundle it provides the northing and easting of the centroid of GB postcodes. I converted these OS grid references into longitude and latitude using gdaltransform and loaded them into a database. I use this to make postcode overlay tiles for use in editors or on maps.
In a recent discussion with Dan Avis I realised that I hadn't done as originally intended and created a postcode finder. When I have the data to hand it seems daft not to go the final mile, so I have. You can see it here. It uses the lovely Leaflet library to display the map and I use a small trick to only show the postcodes at high enough zoom level. Whenever the map is redisplayed I check the zoom level and hide or show the postcode tiles as required.
I have deliberately separated the attribution from the map because the text was too long for the map size I liked. In a while I will have to see what attribution changes are needed, if any, to the various maps I have created as the licence changes.