This was posted on the 18xx Yahoo Group some years back. I'm not sure who originally wrote it.
I strongly recommend that you play with at least one, perhaps more, of the variant rules for 18GL.
1. Let the Tunnel/Terminal/Bridge player choose between the three options on purchase.
2. Put the unselected Tunnel/Terminal/Bridge privates in the pool and let people buy them during the regular stock rounds.
3. Have the ferry private company survive until the end of the game (i.e. allow people to build the ferry late in the game).
4. Swap the first two private companies in the auction order, without changing their price.
5. Have the ferry activate all ferries, not just one.
6. Swap the 10H and E trains, changing their price (E trains become cheaper, 10H trains become more expensive).
#1,2,5 are just for fun. #4 in particular is almost mandatory. The game is basically broken without it, since P1 is such a great private company and very underpriced (it should sell for 40-80, depending on number of players and personal preference). #6 is recommended because in the base game, train buying is so important that the rest of the game can be nearly irrelevant - if I get two cheap 10H trains and you get two expensive E trains, I will win and you will lose.