Here are a few links to sites I like.
The LGB and G Scale Model Railway Club of Australia has regular layout visits in the Sydney area. Why don't you join up?
GRASS-the Garden Rail Addicts of Sutherland Shire - My local group of GR friends
Rails in the Garden is a group of Aussie O and 1 gauge live steamers.
Model sites...
Mark Hobbs' Turrella Tramway line
Geof Coleman's Barron Tableland Railway
The Coramba Creek Timber Co. Railway. Graham Morphett's amazing garden and railway, on the Gold Coast.
James' McInerney's very steep zig zag of The Rurr Valley Railway & Mining Co.
The Sydney Live Steam Locomotive Society.
The Toenail Ridge Shortline Phil Creer's beautiful line in Adelaide
Glen Anthony's NEW Rocky Creek line in Christchurch, New Zealand
Kerry Paterson's Ashburton Forks line. Detailed New Zealand scratchbuilt modelling at 1:24. A beauty!
Goran Jonsson's UTJ railway in Sweden. In Swedish but great pictures.
Tod Hetherington's pages. He builds NSW prototype in 1:32 scale.
Shishi-ga-tani (Deer Valley) Light Rail - A Japanese line in Sydney, by Toshi Yoshioka - a very talented scratchbuilder.
Clive Tucker's Scampington and Chipside Garden Railway - He's in Hampshire, UK. A very comprehensive site.
Matthew Foster's Takasaki Light Railway - He models Japanese narrow gauge.
The Tucson (USA) Garden Railway Society
The Northern Colorado (USA) Garden Railroaders
Other GR sites...
Garden Railways Magazine.
Australian Model Railway Magazine.
Garden Headquarters- a gardening site with GR links
Real Aussie Railways worth visiting...
Puffing Billy Vic.
Pichi Richi SA
Glenreagh Mountain Railway NSW
Dorrigo Steam Museum NSW
The ABT railway, Queenstown TAS.
..and some from around the World....
Those fantastics little trains of Wales.
The Georgetown Loop Railroad, Colorado USA
Driving Creek Railway, Coromandel, New Zealand. Could this be the ultimate BIG backyard railway?
The Bay of Islands Vintage Railway, New Zealand