(MONEY Magazine) – Whether or not oat bran really clears the fat out of arteries, it can sure bulk up your bank account. Or it would have if you'd invested in oats a little over a year ago, when a futures contract went for $1.85 a bushel at the Chicago Board of Trade. By last June the price had shot up to $3.79 a bushel, all on the strength of the reported benefits of oat bran for cholesterol- clogged hearts. Herewith some other windfalls and shortfalls from calendar '88. (MONEY's year-end listing of more conventional investments appears on page 36.) Real estate. California's sprawling, smoggy Orange County led the nation in housing appreciation, with the median price of a single-family home up 32% last year to $226,200, according to the National Association of Realtors. Denver was at the other end of the slope with an 11% decline to $81,100. Also in eclipse: such sunbelt cities as Houston, Miami and Phoenix, where a 0.5% overall slide hardly reflected the toll on the costliest pads (see the mansion depicted on page 15). One sunny exception was Waxahachie, Texas, where real estate values doubled after the government announced it may build a $5 billion superconducting supercollider there to study the mysteries of subatomic particles. Fine art. Contemporary art had a good year, appreciating 41% on Sotheby's index. Jasper Johns' 1959 painting False Start fetched $17 million -- the highest price ever paid for work of a living artist. Lesser-known American painters showed gains too: Harry Shokler's silkscreen Coney Island, of which 100 were printed circa 1940, went from $350 in '87 to $1,000. And works by members of the Cleveland School, a group of social realists from the 1920s and '30s who captured the brawn of heartland industry, doubled in value -- some to the low five figures. Vintage powerboats. Another American classic, vintage mahogany-hulled speedboats, raised quite a wake. These throaty, leather- and brass-appointed beauties from the 1920s to the '50s -- known to aficionados as ''woodies'' -- gained 10% during '88. But experts like Gary Scherb of Sarasota's Old-Time Boat Co. could still find bargains -- like the 19-foot Chris Craft Capri Runabout that he bought for $5,500 in '87 and faithfully restored. It is now worth $11,500. Gems. A big winner was tsavorite, a rare garnet variety found mainly in East Africa. The price of a grass-green, well-cut carat gleamed 20% brighter last year, rising to the $1,800 to $3,000 range. But though retail prices of tsavorite have climbed steadily for several years, gemologist Richard Drucker, editor of the Gem World International Guide, thinks the stone may have peaked. Wholesale demand is flattening, and Drucker expects tsavorite to be replaced in buyers' hearts later this year by more economical dazzlers like chrome tourmaline (only $1,000 to $1,200 per carat). Thrillers. Horror freaks pushed the price of a first edition of Stephen King's 1982 Dark Tower to $525, up from $400 in '87. Even a second edition could bring $200, provided it was in pristine condition with an unblemished dust jacket. Financial fancies. The latest proof that sentiment and investing don't mix was the New York Stock Exchange performance of the Boston Celtics basketball team. Shares in the Celts' master limited partnership -- which raised $48 million when offered for $18.50 in 1986, the last year the team was world champ -- plummeted to $13.75 by the '88 close. Collectibles. Finally, anyone who thought the world of collectibles wasn't perverse found out better in '88 as plastic bric-a-brac from the Fabulous Fifties, like the $33 handbag on page 15, staged a comeback. Their allure? Pure nostalgia, says Lyndi Stewart McNulty, author of Plastic Collectibles (Wallace-Homestead, $17.95). ''Try to find things that define a place in time -- brightly colored plastic radios or Beatles dolls,'' she advises. The watchword, in short, is kitsch.