Want to invest in a green industry that employs the latest technology, reduces U.S. oil consumption and is priced very attractively? Look no further than the railroads. Laggards for decades after the 19th-century boom ended, they're hot again.

"There was steady traffic growth until last year, and the trend looks good once the economy gets back up to speed," says Kenneth Kremar, an economist who follows the railroad industry for consulting firm Global Insight. Perhaps that's why railroad stocks have largely escaped the battering that other sectors have taken so far this year.

Of course, their business could still be hurt temporarily if the economy deteriorates further. But eventually, says Kremar, "we'll see a pickup in demand, especially in the kinds of commodities railroads carry."