If you're a points and miles enthusiast, chances are you've had a friend ask about "the best credit card" to get. My answer is always, "that depends." I try to determine what their goals are, then recommend a card that I think would work best for them.
Of course, I don't allow myself to be influenced by whether I can benefit from the recommendation. BUT, when I end up recommending a card I carry, I usually check to make sure that I can't refer them to the card. Often times "refer-a-friend" offers are worse than the best currently available public offer. But sometimes they're equal to, or better than, the public offer. For instance, Starwood is currently promoting a "refer-a-friend" offer in which the cardholder gets 5,000 points while the referee gets a 30,000 point offer:
This is equal to the current best available offer, plus you get points for referring your friend/spouse/colleague, etc. In such cases you're leaving points on the table if you don't remember to make a referral.