O14 group member Bob T has pointed out a very useful publication available from the HSE which provides Guidance on selection, installation and maintenance of rail track and associated equipment for use underground in mines. It provides a valuable insight into many aspects of prototype narrow gauge track construction some of which is equally applicable to above ground track.
This link has lots of photos by Geoff Plumb of various British Industrial Systems including the 2′ gauge Leighton Buzzard Light Railway. Many of the photos are in colour and provide a superb model reference whatever the gauge.
Le P’tit train de la Haute Somme is a preserved 60cm gauge sugar beet line (with WW1 military origins) in the Somme area of France. As well as steam and diesel stock it has an extensive museum with plenty of interesting 60cm/2ft locos and rolling stock (and some O14 models). A trip on the line is particularly interesting as the line has a Darjeeling style reversing zig-zag to help it climb out of the valley onto the plain above.
The society are also the publishers of the Voie Etroite magazine so there are plenty of current/back issues and other tempting reading material for sale.
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.
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.
Industrial Narrow Gauge Railways is a useful web site which holds information regarding current prototype industrial and commercial narrow gauge railways operating throughout Europe, including many which are 60cm/2ft railways