Platforms 1 and 0 at Cardiff Central, UK
Platform 0 was originally rebuilt for use on match-days at the Millenium Stadium in Cardiff (a few minutes walk from the station). However, it was quickly realised by the station management that integrating Platform 0 with the rest of the station and making it a normal service platform would increase capacity and flexibility at the station. In order to keep the platform numbering in sequence, it was decided to number this new platform zero - the only example I know of of a platform 0 in the UK.
This is one of the four big passenger enhancements seen on the Great Western Main Line since privatisation. The other three are the new Platform 4 at Swindon, building a new station at Bristol Parkway, and re-opening platforms 13 and 15 at Bristol Temple Meads.
Photo by Timothy Vince (le_random@yahoo.co.uk)