The Ashover Light Railway Society have just updated their website which includes news about their first engine. The site contains some useful background information on this classic Colonel Stephens railway.
ww2ft Listing is a site dedicated to listing all 2ft, 1′ 11 1/2″, 600mm & 610mm railways broken down by country. There should be enough prototypes for everybody.
Update 8 Jun 2014 – This site seems to have disappeared but there is an archive version here
Narrow Gauge Heaven is a website dedicated to narrow gauge railways throughout the world, although currently there is more on UK narrow gauge railways than those in other parts of the world. It has the largest narrow gauge photo gallery on the web, with contributions from over 30 railway photographers.