Libertarians or liberty sympathizers who are undergraduates or recently graduated: the Institute for Humane Studies is accepting applications for their summer seminars. They're week-long, packed with lectures and discussions, and a tremendously fun and edifying experience. The two I've been to both definitely rank among the best weeks of my life. They're free (except for travel), and they try to get ideological diversity among attendees (so you shouldn't feel the need to misstate your beliefs on the application). If you've got any other questions about the seminars or the applications, just ask (here, in PM, or by email: I use gmail and my username).