Matt Yglesias has some excellent advice for college students looking at a career in blogging. Since I don't quite have a career in blogging, my advice should most definitely be taken with several grains of salt, but I do have something to add to one of the things he said:
Note that if you want to go to law school, getting good grades in college is probably important. If you want to be a writer, then writing stuff that’s interesting and getting professional writers to read it is important. I got the worst grade of my whole college career in Theda Skocpol’s class on American social policy, and that’s never stopped me from writing about American social policy—nobody’s ever asked or cared whether professors liked my essays.Two things about that. First, as far as I can tell he's totally correct about grades. They might matter for postgrad admissions, especially for those planning to go immediately after college. But mostly, they won't matter very much in your life. My pre-grad school career consisted of working on Capitol Hill; I did a lot of job hunting (and wound up with two excellent positions over the four years plus I spent there), and as near as I can remember no one ever asked me about my grades.
However. Your grades won't matter much if at all, but what you learn really will matter. If you want to be a reporter, it'll help quite a bit to know more about the world. But especially if you want to be an opinion writer, the greater your knowledge base going in, the more you're going to have something useful to say going forward. My guess is that Yglesias may have received a lousy grade in Skocpol's class, but he did in fact learn quite a lot from it, and from his undergrad education in general. Not just facts -- you can always pick those up on the fly -- but complex ideas, and different ways about thinking about the world. Indeed, I strongly suspect that for most undergrads, "learning stuff about the world" is a far, far better career choice than "getting good grades," including the stuff (say, East Asian history, or more than one year of economics, or cognitive psychology, or feminist political theory) that doesn't appear to have any immediate application to whatever it is you expect to be doing in the next five years. Even if you never actually use the stuff you learned, the practice you get in learning to see the world through various lenses is going to be highly useful.
Hey, at the very least you can give your blog posts cool Weberian titles such as "Blogging as a Vocation" instead of having to resort to Rutles quotations.
Update: Robert Farley cautions not to take the advice about grades too far.