A well-crafted watchlist is critical to smart investing: It can help you find attractive buying opportunities, and it can save you from rushed, emotional decisions by slowing down the process. The Fool now offers MyWatchlist.com, your free customized hub to follow the performance and Fool news and commentary about the companies you're watching.

But what to put on your watchlist? Today, Motley Fool Special Ops senior analyst Mike Olsen shares a pair of companies that he's added to his watchlist and one that has since made the jump to his Rising Stars portfolio.

One to watch
Although it doesn't always appear to be the case, mortgage underwriters actually look at data before deciding whether to make a loan. Often they get information like background checks, appraisals, and flood histories from CoreLogic (Nasdaq: CLGX), a recent spin-off from First American (NYSE: FAF). And while a pummeled housing market might seem to be a bad time for a company that capitalizes on new mortgages, Mike likes the fact that the company is counter-cyclical; CoreLogic also brings in business related to refinancing activity as well as bankruptcies and foreclosures.

But while the company's share price has remained flattish to down since its launch as its own company earlier this year and looks cheap today to Mike, there's one housing market that doesn't work for CoreLogic: a stagnant one. Without a meaningful improvement or decline in the housing market and with interest rates about as low as they can go (precluding much new refi activity), this one might be at a bit of a standstill. And Mike thinks the housing market could muddle for quite a while, so he's content to watch.

Two to watch
Quarries have, by their very nature, a high barrier to entry. You can't just dig out a new one wherever you want. As a result, companies that run quarries have significant pricing power and rely on proximity to keep business rolling -- even if a builder can get a better price on gravel from a quarry two states away, the transportation costs would overwhelm any potential savings. With more than 300 quarries and distribution facilities, Vulcan Materials (NYSE: VMC) has a wide, deep moat that allows it to pass along its costs to its customers even through bad times.

But none of that matters if nobody's building. Vulcan is heavily tied to residential housing and government spending on infrastructure. Even though the stock is well off its 52-week high, and even though highways will be built as part of ongoing government stimulus funding, Mike needs to see more reason for optimism. State and national deficits are positively enormous, and as with CoreLogic, Mike doesn't see residential markets markedly improving anytime soon. He'll keep an eye on share price and macro concerns before digging in.

And one he bought
Rail America (NYSE: RA) also benefits from a monopoly based on location. The short-line and regional railroads pick up where the big guys (Class I railroads) leave off, delivering material to customers that aren't located directly on the country's largest lines. The Class I railroads consistently pass price increases in excess of inflation, sometimes as high as 7%, and the short-lines are following their lead. They have, as Mike said in his write-up when he added it to his Rising Stars portfolio, "a license to print cash." And yet the company underperformed.

Three years ago, it was taken private by Fortress Investment Group (NYSE: FIG). Fortress brought Rail America's pricing in line with others in the industry, cut some of the fat out of its operations, and leveraged it up dramatically, "rendering the company unprofitable on paper and positively ugly on a cursory glance at its financials."

But despite its heavy debt load, the company is being powered by some attractive tailwinds, notably oil prices near $80, which makes trains far more economical than trucks. And after watching the company intently, Mike felt confident that its recent price was a bargain because, "In my experience, it's a rare day when you can find a stellar business, depressed valuation, and accompanying value catalysts. But today's the day."

And that's exactly why it pays to watch. You can make smarter investing decisions with your own version of My Watchlist, new and free from the Fool. Click below to start following one of the stocks mentioned above: