Mark McCormack - author of the book What They Don't Teach You at Harvard Business School ) was founder and CEO of International Management Group, now IMG, an international management organization that handles the commercial affairs for sports figures and celebrities. McCormack used to keep a set of index cards in his pocket (I read that in his book). Each of the cards was about a particular person he knew, and on that person's card he would write details about his last interactions with them, etc. Whenever he next met one of those people, he used to pull out the index card for that person from his coat pocket, and instantly knew what to talk about with them - he was never at a loss for words.
I came across Noteleaf, a Y Combinator company, today, and it seemed to me that one of Noteleaf's features works somewhat like Mark's index cards. See how it works
One of Noteleaf's founders (Wilhelm C) wrote this blog post which was featured on Hacker News recently:
Pretty interesting post. That's how I got to know about Noteleaf.
- Vasudev Ram