Most investors don't keep tabs on their companies' fundamental value. That's a mistake. If you take the time to read past the headlines and crack a filing now and then, you're in a much better position to spot potential trouble early. Better yet, you'll improve your odds of finding the underappreciated home run stocks that provide the market's best returns.

We can help you keep tabs on your companies with MyWatchlist.com, our free, personalized stock tracking service. Here are three stocks from my own watchlist.

1. CAPS Weekly Top Stock Idea: Power-One (Nasdaq: PWER)
Each week, I cull a top stock idea from the pitches made on CAPS, The Motley Fool's 170,000-member free investing community. Power-One, a pick from November, caught my eye, since its shares have remained unchanged from when it was picked. Power-One, along with competitors SatCon (Nasdaq: SATC) and Advanced Energy Industries (Nasdaq: AEIS) make power conversion and power management solutions. Fellow Fool Jim Mueller believes Power-One is a buy after it beat earnings expectations but fell on lower-than-expected guidance.

To see the pitch selected for CAPS' Weekly Top Stock Idea, click here. If you want to follow my weekly picks, you can subscribe to the series' RSS feed or follow us on Twitter.

2. ATP Oil & Gas (Nasdaq: ATPG)
Like Callon Petroleum (NYSE: CPE), ATP is an exploration and production (E&P) company. Unlike Callon, ATP takes the "E" out of the equation. It does this by buying proven, yet undeveloped, offshore fields and bringing them into production. ATP Oil & Gas has long caught my eye. The company's story is fairly well-known. Last year, ATP Oil & Gas was expected to drill four wells that would transform the company into a cash flow machine. ATP Oil & Gas finished one well early in the year, but then the disaster in the Gulf of Mexico with Transocean's Deepwater Horizon happened, and all drilling ceased. Drilling has since resumed. I believe ATP is undervalued and recently purchased long-term call options on the shares for my Rising Star Portfolio. To read my buy recommendation, click here, and click below to add ATP Oil & Gas to your watchlist.

3. SandRidge Energy (NYSE: SD)
SandRidge Energy is run by Tom Ward, a co-founder of Chesapeake Energy (NYSE: CHK) with Aubrey McClendon, and board member until 2006. Last year, SandRidge made several acquisitions designed to shift the company's primary focus from natural gas to oil production. SandRidge now has a sizable location in Texas and Oklahoma to search for oil. It expects that its production will swing from mainly natural gas to mainly oil in 2011. If all works out, this company could take off as oil has been rising with the turmoil in the Middle East.

My Foolish bottom line
If you're looking for more information on these companies, add them to your watchlist to keep up with any news in the coming weeks.

Dan Dzombak's musings and articles he finds interesting can be found on his Twitter account: @DanDzombak.

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Chesapeake Energy is a Motley Fool Inside Value choice. The Fool owns shares of Power-One. Motley Fool Alpha owns shares of Chesapeake Energy. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.