Are there any rules to reduce the luck component is Settlers of Catan?
I know there is one stated here, but I didn't understand this. How does this work? Are there any others?
There is actually a commercially produced event deck. When using it, you reveal a card every turn to get a number from 2-12 instead of rolling the dice. A card that reshuffles the deck is mixed in the bottom 5 cards, so the exact composition when the deck gets thin cannot be exactly guessed. (The cards also feature events that affect the game in other minor ways, if you choose to use them that way.)
Other games in the Catan series explore the idea of providing resources or compensation for players who strike out at the dice. Cities & Knights of Catan features an upgrade that gives you a resource of your choice whenever a number that doesn't produce anything for you is rolled. In a similar vein, Settlers of America gives any player Gold tokens who otherwise strikes out on a turn; gold can be later traded for other resources.
I guess you mean this one https://boardgames.stackexchange.com/a/551/3329
The idea is to set up a card deck with one card 2, two 3, three 4, five 6, six 7, five 8, four 9, three 10, two 11, one 12. That's a total of 36 cards. If you use that deck you'll have the same probabilities than adding two dices, but you may use it in a series, discarding every card that comes up. So now you are sure that the probabilities will be the statistical results.
A side-effect (probably not desired) is that if the deck already showed several 6s, for example, you'll know how that few will be shown until the deck is completely discarded and reshuffled.
Letting players trade "future" resources can help a lot. Trading someone a future resource means you're promising to give them that resource the next time you generate it (and when it's one of your turns).
For example, suppose you have a wheat, a wood, and a sheep, and you need a brick to finish your settlement. You have a settlement on a 6 brick, but the dice have been against you the whole game, and you just haven't rolled many 6's. You've had bad luck.
Meanwhile, someone else's 12 brick just rolled, but he can't do anything with it right now.
Ordinarily, you're just stuck passing the dice and waiting for your 6, but with future resources, you can sell two future bricks -- your next two bricks -- for your opponent's brick in hand. You're able to cash in on what your 6 brick should roll in the future, rather than just what it happened to roll in the past.