Here are some considerations:
- Don't turn your nose up at small talk. A comment about the weather can lead someone to reveal that they're not used to it because they're from somewhere else. Maybe you know someone in that city or used to live there yourself.
- Show enthusiasm for your own interests. A story about your fishing trip a few weeks ago could bring other anglers into the open. Be careful not to go on and on, though.
- A business networking environment is a natural locale to ask how they got into their current job, what they studied in school, or what other business associations they belong to. Even what magazines they subscribe to.
- Be sure not to pepper them with questions. You want the revelations to come from a natural flow of conversation. Instead, try working into the conversation stories (SHORT ONES!) about your interests. For example, "That's interesting that you mentioned great comedies. I watched Monty Python's Holy Grail again this weekend for the twentieth time." If they're a Python fan, too, they'll let you know. Or try this conversational gambit, "I was almost late because I had to set my DVR to record Survivor (go Aitu)."
- Don't be disappointed if a revelation about your favorite pastime elicits no response. Move on to another topic, or ask them what kind of movies/sports/hobbies they like.
- While you don't want to interrogate, there are a few questions you can ask that are non-threatening. Ask what they like to do when they're not working. Find out if they are from the area - often, they'll tell you the story of how they got here. Have they been to any good cultural events in town? Can they recommend a good restaurant?
- If you have only a few obscure interests (Aztec love poems or Roshambo tournaments), you're going to need to cultivate a few more widely-shared activities. Gardening and bird-watching are some of America's most popular past-times. Find something that you enjoy and can share with others.