Now is the time for investors to turn skyrocketing oil prices into income. One of the best ways for income investors to earn a hefty paycheck is through master limited partnerships (MLPs).

Here, we look at four MLPs that offer yields of at least 7%: Linn Energy (LINE), Boardwalk Pipeline Partners (BWP), Energy Transfer Partners (ETP) and Inergy (NRGY).

Like regular stocks, MLPs offer investors -- or in this case limited partners -- payments that are similar to dividends, only taxed differently.

Because they are partnerships, MLPs aren't subject to state and federal income taxes. The funding costs are relatively cheap when compared to a regular dividend stock. And yet, some MLPs can generate income with even the highest-yielding dividend stocks. It's just a matter of finding the right ones.

With that in mind, here are four U.S. energy MLPs that yield more than 7%. Each company boasts a healthy bottom line already, and should continue to generate income as oil prices rise. As they generate income, so too will their shareholders.

Linn Energy, an independent oil and gas company, develops and acquires oil and gas properties across the U.S., including Oklahoma, Louisiana and California. The master limited partnership offers a generous 7.5% yield, with a quarterly distribution of $0.66 per share. Having more than doubled its payout over the last six years, and given that the company has increased its annual earnings by an average of 40% for the past five years, there's plenty of room for Linn Energy to grow.

Boardwalk Pipeline Partners, a natural gas transporter, carried approximately 10% of the natural gas supply in the U.S. in 2010. The company owns more 14,000 miles of pipeline that spans four states and serves numerous others, and has a net income of $220 million. That's why Boardwalk recently upped its quarterly dividend to $0.53 per share -- a yield of 7.8%.

Energy Transfer Partners, a Texas natural gas company, recently fell short of earnings expectations, but still posted revenue that was 25% higher than the same quarter a year ago. The MLP still has a distribution yield of 7.5% and a whopping $3.58 annual dividend. Energy Transfer's average dividend yield over the last five years is 7.4%. Energy Transfer is currently trading well below its 52-week high of $55.50. With earnings in 2012 expected to rise to $2.31 per share from $1.55 last year, it's unlikely Energy Transfer is going to cut back on its quarterly distribution to shareholders anytime soon.

Inergy currently has an eye-popping 15.7% yield; it's probably unsustainable. But Inergy does have a strong dividend history since it began paying a dividend in 2001. In fact, the company's yield hasn't dipped below 7% in nearly five years. That's because Inergy is one of the leading propane gas retailers in the U.S., and also operates a natural gas storage and transportation business.

While the stock has lagged in the past year as it tracks natural gas prices, which have been crushed of late, Inergy's earnings per share are expected to grow 27% over the next year as natural gas begins to show some signs life. That should inject some life into the stock price, and prevent the superhuman dividend from falling too far.

In a time when 10-year Treasury notes are yielding little more than 2% -- their lowest yield in over 30 years -- dividend stocks are a far more profitable alternative for income investors these days.

And, with oil on the rise and natural gas starting to bounce back, it's also a good time to invest in energy. So finding energy stocks that pay dividends is a way for investors to take advantage of these two fast-moving trends.

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