Over the years, I have taught myself to overcome my introvert tendencies and talk to new people at conferences (which is the one of the most important reasons to go). I've become somewhat of a decent networker, and have met many people I later worked with later on.
My real weakness these days is in the follow-up. In my head, I know it is important to follow up with the people I met in order to capitalize on the connections I made at the meeting. But once I am home, away from the thrill of the moment, I find it easy to procrastinate and indulge my introvert tendencies. It is easy when someone has asked for a reprint or preprint, but much harder when there is no compelling reason to contact someone. This is definitely something I need to work on, since each step in my career has only strengthened my understanding of how important networking is to any human endeavor.