Why oh why have I never realised before that the receipt that they give you when you buy an annual travelcard is worth 1/3 off other rail travel? I had absolutely no idea, and it is never advertised anywhere!
More info about these mysterious Gold Cards here.
So here's an example of how much money I have been chucking away because I didn't know this.
I have an annual zone 1-2 London oyster card and regularly go to visit my parents in Buckinghamshire. Normally DH and I pay about £36 to both go. This time we queued up at the counter (as the discount isn't available at the ticket machines) and bought tickets waving these Gold Cards and also stipulating that we only wanted the tickets to run from the edge of zone 2 instead of from the terminus station. Again apparently no-one does this as the staff were really confused at the ticket barrier about this, but eventually conceded it was all in order and let us in. £19 total it cost us. We saved £17. This on a journey we make monthly. Grrrrr. I hope this helps some other MNetters save £.