Dave,
Your comment about sports is apt. Joseph Epstein wrote an essay about the food of New York for the WSJ called Good Grub and the Spirit of Capitalism, asking why New York City has so many more world-class restaurants than his home city of Chicago. His armchair explanation is “super” capitalism:

I don’t know if Thurman Arnold or Joseph Schumpeter or any of the other theorists of the inner mechanics of capitalism have hitherto spoken of it, but there is, in capitalism, operating at a sufficiently intense level, a spirit of competition that can bring out the best in everyone, at least in those realms where you cannot fake it. Something similar operates in professional sports — the Major Leagues, the NBA and the NFL. Room exists only for the best.

Something akin is happening in academia, I think, at least at the top end of colleges and universities. (And, like professional sports, there is a rapidly growing, poorly compensated “minor league” of people who work primarily for “the love of the game.” Unlike sports, though, the “objective” measurements of talent, ability, work ethic, productivity, etc., are far less clear or standardized, people almost never go into academia with the assumption that it will likely be a time-limited season of their life, and the coaching/mentoring apparatus is far less developed. What would the academic equivalent of a hitting coach be? Or a batting practice pitcher? But I digress…)

Janine and Kelly, you make excellent points about the difficulty (and probable futility) in mastering such enormous amounts of material. I remember from my undergrad years some critic remarking that Milton was probably the last person to have mastered the complete literary canon of his day, in the West, anyway. (Harold Bloom might disagree.) So, perhaps rather than extensive reading for content, maybe a better question would be:

What is the most strategic reading for an undergrad? And, alongside it, what are the most strategic research and study skills to develop?

So, here’s two ideas that might get rejected: in English lit., the “return on investment” in reading Shakespeare and the King James Bible is perhaps the greatest, because of their influence on the following 400 years. And, if you’re an American, a good paperback history of England also has a huge ROI, so that you can put a social context around the literature.

That being said, getting used to primary literature during undergrad will be helpful (though I must admit, painful). Start by going to http://www.pubmed.com and looking for review articles on topics that interest you (for instance, diabetes and obesity or cancer stem cells or HIV vaccines). Once you find a good review, you can always follow rabbit trails in the references, and who knows where you will end up! Subscribing to news feeds from professional organizations is also a good way to get an idea of what’s going on in that field.

The other possible problem is that not all universities subscribe to the journals. If you live near a major research university (like Penn State, VA Tech, Penn, etc…) take a trip to their library – once you’re logged on to their networks, almost all of the articles are available online.

In physics, I would say that you need to get all the quantum mechanics and other advanced courses you can. This is a problem primarily for students at small colleges. Consider doing a 3+2 program where you finish at a major school, or else get the a professor to do a directed reading course with you. Also, every physics major should learn how to program in a line-based language like C or Fortran.

If your department has a colloquium series, attend it so you learn what are hot topics in the field.