JEREMY Grantham, chairman of Boston- based investment firm Grantham, Mayo, Van Otterloo & Co., suggested earlier this year that the world was witnessing "the first truly global bubble". Here are seven more bubbles for investors to ponder.1 Economy, Business, First, and Now Scooter Class

Wealthy air traveLlers used to turn left rather than right when boarding an aeroplane. For a while, the lucky few climbed the stairs to the second deck for their unlimited free booze, lay-flat beds and personal DVD players.

These days, you are nobody without a VIP pass to the private apron at the airport, although for now you can still get by with a NetJets Inc. account rather than your own $20 million Cessna Citation X. Private planes even have their own slang; jet setters talk about "taking the scooter" to their villas and yachts.

It's not just Hedge-Fund Guy and his trophy wife demanding splendid isolation from cattle-class rubberneckers eyeing their chocolate-dipped strawberries. Revolution Air, a charter company, will fly more than 20 US kids to summer camp this month, at about $8,000 a hop, the New York Post reported last week.

You know there's a bubble when the stewardess is serving Kool-Aid rather than Cristal, and the scooters that kids are using on holiday have wings and engines, not kick plates and T- bars.

2 Skull-duggery<$z$>

Take a life-sized platinum skull that looks eerily like Hedge-Fund Guy. Stud it with 8,601 diamonds weighing 1,106.18 carats. Give it a snappy title such as "For the Love of God" and, as long as your name is Damien Hirst, you have a recipe for turning $20 million of materials into a $100 million windfall.

"You have to get the price right, or it will come back into the market," Hirst told Bloomberg News reporter Linda Sandler. "A lot of people buy things and flip them."

You know there's a bubble when artists are trying to set their prices so high that there won't be a secondary market for their work>

3 Vinegar Versus Champagne

If Hirst designed a vegetable display, it would look like the shop window at the just-opened Whole Foods Market Inc. branch in Kensington, one of London's ritziest shopping areas. Analysts at JPMorgan Chase & Co. calculate that Kensington could contribute as much as 1.8 percent of the food retailer's total sales. Whole Foods said last month that second-quarter revenue was $1.46 billion.

It's a food-porn cathedral dedicated to organic this, natural that and locally produced the other. On a Monday afternoon, the place was packed with gym-buffed yummy mummies driving designer pushchairs and doing battle in the produce-crammed aisles with trolley-dragging wealthy retirees.

The zeitgeist-defining product among the free-range bananas, organic spring water and corn-fed soup is a 60-year-old Vecchia Dispensa balsamic vinegar, costing almost $200 for a triangular 100 millilitre bottle stoppered with red wax seals.

You know there's a bubble when an overgrown US chain store can sell antique vinegar to Britons at 32 times the price of Nicolas Feuillatte champagne.

4 All Hail Emperor $>

Stanley Ho, the Hong Kong entrepreneur who made his billions running casinos in Macau, last month paid HK$13.7 million ($1.8 million) for a chair, beating Christie's International's presale estimate of HK$12 million.

It was a rather special chair. Emperor Kangxi graced the gilt-incised brown lacquer throne when he ruled China between 1662 and 1722. Still, Ho could have picked it up for just $43,700 when it sold in 1994.

You know there's a bubble when a gambling mogul drops a couple of million dollars so that his buttocks can polish the seat of royalty.

5 How Did You Ever Live Without <$>

You work in the marketing department of Chrysler Group, the US carmaker that DaimlerChrysler AG paid $36 billion for in 1998 and is now offloading to private-equity firm Cerberus Capital Management LP. How do you plan to entice drivers to hand over $26,145 for a new Sebring convertible, impressing your new owners and hanging on to your job after the changeover?

"Heated Cup Holder," says the double-page advertising spread in the New Yorker magazine. "Flip a switch and this feature will maintain your drink's temperature up to 140 degrees. It can also cool to a refreshingly chilly 35 degrees."

You know there's a bubble when the latest innovation in automotive engineering is a gadget to keep your bucket of Starbucks Corp. Costa Rica Tarrazu hot enough to guarantee third-degree lap burns when you brake for that road-running child.

6 Gross Has Got Investing Lid<$>

Bill Gross, manager of the world's biggest bond fund at Pacific Investment Management Co. in Newport Beach, California, paid about $2.5 million for a collection of British stamps, buying most of them since 2000. This week, the philatelist auctioned the set in New York for $9.1 million.

"It's four times profit," Gross said of the price. "It's better than the stock market." If he had invested the $2.5 million in a Standard & Poor's 500 Index tracking fund at the beginning of 2000, he would have barely broken even by now, and would have been down to $1.4 million in October 2002. In bonds, his $104 billion Total Return Fund delivered a 6.9 percent average annual return in the past decade, according to Morningstar Inc. data.

You know there's a bubble when tiny, lickable portraits of Queen Victoria are a better store of value than stocks or bonds.

7 The Bubble in Bubbles

The word "bubble" has appeared in 94 Bloomberg News headlines this year, up from 40 in the year-earlier period and from 85 in all of 2005.

You know there's a bubble when there's a bubble in usage of the word "bub."

(Mark Gilbert is a Bloomberg News columnist. The opinions expressed are his own.)