If you're young and looking for a summer job (or any job) here's one approach: reach out to somebody you really admire and ask if you can be his/her bitch for a few months. Say you'll be happy to do grunt work so long as you get lots of face time with him/her. Say you're a self-starter who won't be a nuisance but rather will find a way to make their life / work easier. Identify a few things that you think you could help them on (anything involving technology / blogs is good, or logistical help, or communications outreach).
Learning on the job comes primarily from the people you get to work with. So pick out a few people who impress you and send them an email and see what they say! Don't worry if their exact line of work isn't on your radar screen; the goal is to work with the most impressive person you can. I guarantee you'll learn more by being a supercharged personal assistant to someone really smart / interesting than you will by doing a generic internship.
Unrelated but since we're talking about careers and young people: Your major in college doesn't matter!
OK, maybe it matters a little for your first job, but still, I can't believe the number of people who say, "As a History major I'm screwed because I now want to go into finance but can't because I didn't major in econ or business" or "No one wants to hire an English major." Bullshit! Employers hire people. Stand out, be remarkable, knock their socks off. Forget about your major. If you went to a liberal arts school it especially doesn't matter, since to "major" in something means to take a very small number more classes in your major topic than in any other topic.
And since I find myself in ranting mode: Economics is no more practical an academic undergrad major than English! Don't major in Econ thinking you're studying the most useful subject for getting a job. Major in what you find interesting.