Nati Harnik / AP

"Don't count out Warren Buffett." 

That's how I began my post one week ago as I launched our '2007: The Year in Warren' countdown, going from #10 to #6 of the top 10 trends and events of the year, as covered here on Warren Buffett Watch.

That was before Buffett showed us again why you can't count him out, as he turned what should have been an uneventful holiday week into a whirlwind of activity.

So, slightly delayed, but fortified with new material, here comes the 'final countdown' from #5 all the way to #1.

#5  RIDING THE RAILS

Warren Buffett placed a big bet on a railroad this year, picking up shares of Burlington Northern in a series of purchases that has Berkshire owning almost a fifth of the freight carrier's outstanding stock, with the possibility of going to 25 percent or more.

It's not a sector-wide bet, in keeping with Buffett's preference to buy with laser-like precision rather than broad sweeps.  Even as he was buying Burlington, we learned he was selling shares of two other railroads: Norfolk Southern and Union Pacific.

Burlington fits the classic Buffett model: a well-run, simple-to-understand industrial company that will benefit from the better economic times Buffett knows are coming back sooner or later.  The railroad's protection from competitors, who would have to spend a lot of time and money building new tracks, is also a key factor, as it is in many Berkshire investment decisions.