Tomorrow is Valentine's Day, that one day a year that generates so much adoration from romantics and so much scorn from those who've chosen not to couple off. Having once been one of those kids who only got the sympathy valentines, I wanted to look at stocks that similarly get no attention -- even though they deserve it.

Unloved aristocrats
If you read enough articles at the Motley Fool, you've undoubtedly run into one contributor or another talking about the Dividend Aristocrats. These darlings of the S&P 500 boast at least 25 consecutive years of raising their dividends every year, making every income investor happy by showing their love every quarter in the form of cold, hard cash.

As you'd expect, many of the Dividend Aristocrats are household names. AT&T used to provide service for just about every phone in the country, while you can probably find Procter & Gamble products in nearly every household in the U.S., as well as millions more abroad.

But for whatever reason, some of the Aristocrats and other stocks outside the S&P 500 that boast similarly long records of raising their dividends just haven't gotten any respect. Let's take a closer look at five of them.

1. American States Water (NYSE: AWR), 57-year annual dividend increase streak, 3.1% dividend yield
As a water utility, it's hard to get more boring than American States Water. The company provides water to a dry region of the country that includes parts of Arizona and California. It's provided shareholders with a 10%+ return annually for the past 20 years.

The scarcity of water with increasing populations has made forward-looking investors look more closely at the companies that provide it. With huge growth opportunities and dependable cash flows that seem poised to increase in future years, American States Water may get exciting in a hurry.

2. Northwest Natural Gas (NYSE: NWN), 56-year streak, 3.7% yield
Another utility, Northwest Natural Gas also serves the West Coast, with its primary distribution to Oregon, Washington, and California. With a 12% average annual return over the past 20 years, it's been a solid performer for shareholders.

Natural gas prices have been in the doldrums, with a huge supply glut and fairly weak demand. But eventually, price imbalances will spur demand growth, and Northwest Natural Gas could profit from the uptick in gas use.

3. Dover (NYSE: DOV), 56-year streak, 2% yield
Dover is an example of a low-profile conglomerate. It has a diverse set of businesses ranging from powertrain systems and internal engine components to refrigeration and heating systems and consumer-electronics speakers and receivers.

With better than 11% annual returns for shareholders since 1992, Dover investors can't complain about its success. Yet with solid prospects for growth, it's not a dead-end stock, either.

4. Parker-Hannifin (NYSE: PH), 55-year streak, 1.9% yield
Parker-Hannifin is another quiet industrial-oriented company. It focuses on hydraulic components for transportation and aerospace applications, including aerodynamic control systems and climate control equipment. With nearly 15% in 20-year average annual returns, the stock has done very well by shareholders.

One interesting growth driver that could push Parker Hannifin forward is its hydraulic hybrid drivetrain that it developed with Eaton. As hybrids become an important part of transportation in the U.S. and around the world, it's a definite chance for Parker-Hannifin to get some higher-profile business under its belt.

5. Cincinnati Financial (Nasdaq: CINF), 51-year streak, 4.9% yield
Nothing tells you more about a stock than how it gets through a crisis. For insurance company Cincinnati Financial, 2011 marked a tough year as it suffered its second-worst quarter in 12 years. But the insurer has learned a lesson from Warren Buffett and others, putting a quarter of its portfolio into dividend-paying stocks rather than relying solely on bonds and other low-paying income securities.

Despite a tough year, the stock has paid off for long-term investors, rising nearly 10% annually since 1992. With a bounce-back in rates likely, the coming years could be even more lucrative for Cincinnati Financial.

Fall in love again
Dividend-paying stocks deserve your attention not just for their current income, but also as long-term investment plays. These stocks aren't well-known, but by their past performance and their future prospects, they may be worth getting to know a lot better.

For more smart long-term investment ideas, check out the Motley Fool's latest special report. We highlight three smart stock picks for retirement investors, and we won't charge you anything at all for it -- but it won't be around forever, so read it today while it's still available.

Tune in every Monday and Wednesday for Dan's columns on retirement, investing, and personal finance. You can follow him on Twitter here.