Very soon 1,399 of your best friends will be converging on Washington DC to talk about all things Drupal, web, business, yada yada yada. What could be more fun than that?! Well, for some people, believe it or not, the thought of so many people or the thought of having to do anything particularly social with people that they don't already know, is a bit overwhelming/unappealing. Under normal circumstances I fall into this category. Starting a couple years ago at my first big Drupal function, however, I made a deliberate decision to try to overcome this tendency. As it turns out that was one of the best decisions I've ever made in my life. The effects which have followed "forcing" myself to go say hi to more people than I normally would back then are still with me to this very day.
Hopefully anyone reading this won't confuse what I'm saying as an endorsement to run up to everyone they've ever wanted to meet and harrass them - if you're already a social butterfly - you probably don't need to force yourself to be more social - that would just be obnoxious ;-). But by all means if you're hanging around somewhere - don't hesitate for a second to say hi to whomever is around you. ("So what do you do with Drupal?" is always a nice starting point)
Couple more tips: