There is a new website for hillwalkers listing 1564 peaks in the UK. It provides a lot of links to maps (Google, Streetmap and Get-a-Map) and to the Geograph website for photos.
Most lists of hills in the last century or so have been using criteria based in feet, e.g. the summit height. Such lists include the Munros, Corbetts and Hewitts. This website uses prominence in metres which is compatible with modern Ordnance Survey maps.
I have been a fan of using prominence as it is usually a pretty good indicator of how distinct a hill or mountain is. A good example is Sugar Loaf in South Wales which is a mere 596 metres high yet commands views in all directions due to its high prominence of 413 m.
