Some do it for a burrito. Some do for it for lecture notes. Some do it for Thursday night fun. Next time you need something, instantly broadcast to the 1,000 people nearest you. Advice, a running buddy, beer, concert tickets, textbooks, or a date for Thursday night.
We all have unique skills and knowledge to offer. See what others around you need, and help fulfill them. Do it for kindness, for making a new friend, or just for cash.
Build your profile. Let others know what they can ask you about. Create and join groups that matter to you, and help build your community.