Now I thought that both QGIS and GRASS could do map projections and reprojections but if your asking then I guess not since I know little about either. There is a GDAL library which has a set of utilities to do map projection stuff. Also, NASA has their G Projector.
But again I have not used either. Flag down a member here called Waldronate who knows a lot about it and has written some apps which do some of them.
I write ViewingDale which can do the map zooming and scaling with raster maps instead of vector and can do the google maps type thing but not specifically as an interactive web page online - tho it does have a web server type thing built in. It will do a planet and all thats in it tho.
There is a members map about here where you can stick a pin into the approx position if you feel like narrowing down the UK a bit more. Links to viewingdale and the members map are in my sig.