Some trends are obvious enough and visible to all investors. Others are more subtle but are just as potent, and these often slip "under the radar."

Case in point: Water and energy use is trending lower, and a good example is the City of New York. Water consumption has been dropping on per capita (or per person) basis, basically, for 25 years.

The daily biscuits. With the June deadline for Steve Job's reappearance as Apple (NASDAQ: AAPL) CEO coming on fast, speculation in the media has begun to build that Jobs will choose to retire. That would be a horrifically bad thing for Apple shareholders, who have done very well of late. Sentiment on Apple is holding strong, so at least some people don't think Steve is bowing out.

• Suburban slums -- city centers being revitalized
• Fund roads & bridges NOT mad money stimulus
• Serious Money: Stimulate productivity not consumption
• Should Feds stimulate or stabilize; is there a difference?
• Re-think new stimulus package? Push infrastructure!

Sheldon Liber is the CEO of a small private investment company and the principal for design and research at an architecture & planning firm. He writes the columns Chasing Value and Serious Money.

While many have opined that the water industry will be for the 21st century what crude oil was for the 20th century, water stocks got killed in 2007. Mostly due to a slowdown in residential construction, water infrastructure companies had large drops in profit. That being said, this industry is starting to show decent value.

My pick as the top performer for '08 is Mueller Water Products (NYSE: MWA). The company has taken measures to shore up their financial situation during the downturn in the construction cycle. They reduced expenses, increased cash flow and have strengthened their balance sheet. By trimming the fat and getting much leaner, Mueller is well positioned to benefit long term in the water infrastructure market once the housing market turns.

While I know this is controversial, and no one can pick a bottom, I think we will start seeing some bottom fisherman come in and start buying cheap real estate. If this happens, Mueller may well be a stellar performer in '08.

Aaron Katsman is the lead Portfolio Manager and Managing Director of America Israel Investment Associates, LLC. and Senior Editor of IsraelNewsletter.com. DISCLOSURE: The writer has no position in any stock mentioned as of 12/30/07.

This post is part of our Hottest Products of 2007 feature. Also check out our other Hottest Products of 2007 posts and let us know which product you think is the greatest thing since sliced bread.

When I first discovered the products of glacéau, maker of Vitaminwater, it was the summer of 1998, and there were four flavors of Fruitwater. The lemon ginger flavor was strange, at best, but I could drink an entire cold bottle of watermelon water after a run. Cranberry mint was curious and refreshing. They were lovely, with the tiniest hint of color and no sugar: what I'd always wished for in a bottled water.

Cut to 2007, when, in order to cater to the mass market's taste for sweets and the craze for vitamin-enhanced beverages, glacéau's Vitaminwater has been stocked with sugar and color. This summer, Vitaminwater was being guzzled by all my friends' children at family barbecues and birthday parties. The day-glo orange and green look oh-so much like the Kool-Aid and Gatorade we drank in decades past, and I have to say they're just as sweet. The watermelon water I loved has been replaced by four new flavors, all "naturally" sweetened; peach, raspberry, grape, lime. Sounds like Lifesavers! The kooky Whitestone, Queens management has sold (out?) to Coca Cola (NYSE: KO) for $4.2 billion. 50 Cent, famously, had a big payout thanks to his prescient investment in the stuff (he wanted to put his money in something healthier than his rap rivals' liquor ventures). For Coke, of course, it was just the latest salvo in the next generation of the cola wars (now it's enhanced waters and super-premium juices, but it's still the same ol' Coke vs. Pepsi).

While driving on LA freeways, I sometimes wonder: how strong are these structures? Were they meant to handle the huge amounts of traffic?

I hope so. But I also realize that throughout the US the infrastructure is getting old and needs replacement.

Well, the private equity folks are seeing opportunity. For example, this week, The Carlyle Group announced its Carlyle Infrastructure Partners fund, which has about $1.15 billion under management.

The geographic focus will be on the US as well as Canada, and Carlyle will look to invest in projects for transportation and water.

Actually, this is kind of a new area for private equity and as a result, Carlyle has hired 14 professionals to manage the fund.

More importantly, the opportunity looks vast. After all, Carlyle projects that the US will need to spend $1 trillion on infrastructure over the next five years.

Tom Taulli is the author of various books, including The Complete M&A Handbook and The Edgar Online Guide to Decoding Financial Statements. He also operates DealProfiles.com.

Brady, who dates a supermodel and makes gossip-column headlines as well as sports news, joins Jennifer Aniston in pitching the distilled water with added electrolytes. Replacement of electrolytes depleted in workouts can ease muscle fatigue. Smartwater is the top enhanced water with yoga enthusiasts, and Aniston has lent the brand a sexy, healthy lifestyle image. Brady adds some muscle to the healthy image.

Last week, the mayor signed an executive order banning the use of city funds for the purchase of single-serving water bottles, and also banned the sale of bottled water on city-owned property. It's all part of the city's effort to become more environmentally friendly and less wasteful, and residents who sign an online pledge not to buy bottled water can get a free stainless steel water bottle. The city also recently outlawed the use of plastic grocery bags.

In an interview with Newsweek, Newsom said: "These people are making huge amounts of money selling God's natural resources. Sorry, we're not going to be part of it. Our water in San Francisco comes from the Hetch Hetchy [reservoir] and is some of the most pristine water on the planet. Our water is arguably cleaner than a vast majority of the bottled water sold as 'pure'."

While there are no major public companies that sell only bottled water, companies like The Coca Cola Co. (NYSE: KO) and PepsiCo (NYSE: PEP) could be adversely effected if the anti-bottled water trend catches on nationally. Coke and Pepsi own Dasani and Aquafina, respectively.

Many newsworthy happenings are bubbling up in the pool of activity surrounding clean-water technology. One is that India has launched the world's first floating desalination plant. Kapil Sibal, minister for science, technology and earth sciences, said Wednesday that the barge-mounted plant will produce up to one million liters of fresh water daily, and that the water would be superior to what's now available. The plant uses colder, deep sea water to assist in the cooling and condensation processes, resulting in a more efficient operation and using less energy.

General Electric (NYSE: GE) is supporting an initiative by Dynoil LLC to improve power and clean water resources in underdeveloped countries. GE is contributing solar energy modules and water filtration technology bearing its "ecomagination" certification to Dynoil's efforts to establish self-sustaining water filtration facilities in remote parts of India, Southeast Asia and Africa. Switzerland Guide News reported that Vic Abate, vice president of renewables for GE Energy, said, "We are very pleased and excited to have the opportunity to demonstrate how GE's ecomagination products can enable projects, like Dynoil's alternative energy/clean water initiative. These projects will help improve the health and safety conditions of areas lacking adequate infrastructure, transmission grids and direct access to safe water supplies." (The Switzerland Guide link is a must read!)

Accelerating Technology has reported that researchers at Lawrence Livermore National Laboratory have developed a new membrane material which could revolutionize water purification technology for the long term and reduce the cost of desalination by as much as 75%, when compared with reverse osmosis systems. Reverse osmosis is the current standard water purification technology, which involves forcing water molecules through a restrictive membrane. The lab's new carbon nanotube membranes sort molecules by size and using electrostatic forces. Although the new membranes have reduced pore size, they allow the same flow-through volume as the current, less restrictive membranes. The development could mean energy savings, as less force is required to accomplish standard flow rates. Researchers say the carbon nanotube membrane also holds promise for applications in capturing and reducing carbon dioxide emissions from power plants and similar operations.