The British have done O Scale outdoors for many, many years. I can't help you with specifics about manufacturers, etc., but I bet that if you do a Google search or Yahoo.uk, you'll find lots of information.
SandyR
Lionel collector, stuck in an N scaler's modelling space.
Peco in the uk do an excellent outdoor track available in the US too - I guess its the same as their G scale track which has served well for 11 years on my outdoor layout.
various rail configurations are available code 124 and 143 tho the 124 is perhaps too fine for outdoors.
http://www.ogauge.co.uk/peco.html
I too have had O scale in the yard for the last 2 1/2 years.Main line is About 600 feet. I use the same method described by FG&J, with the exception of using Atlas three rail Nickle-silver track. So far it has held up very well. I also use track power, home run style, with MTH's Z-4000 transformer. everything works, and runs, flawlessly. If you have any questions, don't hesatate to ask.
Bill
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