NEW AND NOT-SO-USEFUL / LYNN SIMROSS : Fruitcakes to Burn, Diapers That Talk

Every year inventors and entrepreneurs come up with ideas they hope will become the new Pet Rock or Cabbage Patch doll. Some become moderately successful products. Others, maybe, should have remained on the drawing board:

* Gotten your share of dreaded holiday fruitcake? Bet there’s one you missed--Grandma Keenan’s Flaming Fruitcake, a fireplace log. Flaming Fruitcake will burn for three hours and has “no calories and no cholesterol.” San Diego inventor Jim Keenan, who developed the sawdust log with imprints of nuts and fruits, doesn’t sell just one, which would be a suitable gag gift. They come by the case, six for $39.95 plus shipping. Grandma Keenan Specialty Products Inc.; (800) 424-2095.

* The Chocolate Patch, a takeoff on nicotine patches for smokers, is another pricey novelty item. This “7-day transdermal therapeutic system for treatment of chocolate addiction” contains seven foil-covered pieces of chocolate and seven adhesive patches. It’s $8.95. Callaghan Promotions, 1601 Henrietta St., Birmingham, Mich. 48009; (313) 642-8556.

* Elvis has been sighted again, but not at Graceland or the Atlanta Falcons’ stadium. His latest appearance is at the Richard Nixon Presidential Library & Birthplace as the unlikely best pal of the ex president. The library’s gift catalogue is full of Nixon-Elvis offerings.

There’s a 22-by-28-inch poster of “The President and the King” shaking hands for $18, an 8-by-10 photo of the duo for $5.50 ($35 framed), 10 note cards for $15. A Nixon and Elvis quartz watch is $45, a “President and the King” T-shirt $14.95. There also are Nixon-Elvis postcards and Nixon and Elvis “together at the White House” mugs at $9.95 each or $32 for a set of four. Funny, there’s not one of Nixon and Spiro Agnew.

Richard Nixon Library and Birthplace, 18001 Yorba Linda Blvd., Yorba Linda, Calif. 92686; (714) 993-9747.

* The Commuter CoverUp is supposed to protect commuters who drink or eat in the car from spills. Its size--more bib than apron--is against it. Only 17 inches long, the Commuter CoverUp won’t keep hot coffee from spilling on your leg and the little “wide catch” pockets at the bottom aren’t effective in catching crumbs. Made of black neoprene and something called “special Intera treated black nylon,” the cover-up does absorb moisture. It doesn’t adjust far enough with its neck strap to “cover any size wearer, whether tall or short” as claimed. $17.95 plus $3.50 shipping and handling. SAMI Inc.; (800) NO-MESS-9.

* The Changing Time Diaper Cover shows and tells you when the baby is wet. Thermocromatic ink causes the cover to change color to indicate when a diaper is wet or soiled. Besides designs that change color, the cover comes in a pattern on which the words “change me” appear. The covers work with cloth or disposable diapers, according to the manufacturer, Diplomat Juvenile Corp. Show and tell is fine. But what was wrong with sniff and feel?

Time Diaper Cover ($5 to $6). Available at Target, Sears and Toys R Us stores.

* Deluxe Corp.’s Stars collection of checks include seven different cartoon characters--B.C., Bugs Bunny, the Flintstones, the Jetsons, the Simpsons, Garfield and Ziggy. There are corresponding checkbook covers. Deluxe, the 78-year-old check manufacturer, explains in its promotion that it is trying to reach baby boomers, who “are refusing to become the ‘serious’ adults their parents were.” Let them grow up. $14.95 for 200 checks and a vinyl checkbook; $28.95 for leather checkbook. In Southern California, they’re available at Bank of America, Wells Fargo Bank, Cathay Bank and First Interstate Bank.

* “The Irreverent But Indispensable Guide to Hair Loss Solutions” purports to identify and evaluate 37 alternatives to hair loss, giving the more than 55 million Americans with balding problems “all the information they need to finally decide whether to go bald gracefully or take immediate action to reclaim precious lost hair.” The book didn’t seem too bad, until we got to the chapter on castration, “the ultimate solution.” $19.95 plus $4 shipping and handling). Eads Publishing Co., 235 E. Colorado Blvd., Suite 1377, Pasadena, Calif. 91101; (800) 423-9400.

* Each year there are thousands of new children’s products. The “DRINK, Mommy!” Baby Nipple Adaptor seems to be one that misses the mark. It is a screw top that holds a nipple and fits over pop and water bottles so a baby can drink from them. The top portion of the Baby Nipple Adapter accommodates a standard baby bottle nipple. However, when the contraption is attached to a regular soda or water bottle, it is cumbersome and hard for little hands to handle. $2.50 each plus $1.50 shipping and handling for up to three adapters. Aspen Shade Developments, 621 Cambrian Court, Sacramento, Calif. 95864; (800) 487-2706.

* Roomies are strange little plush toys in bright colors that come with accessory packages so children can change the mouths, noses, eyes and hair to make their own creations. Not a bad idea, but way too expensive. Basic Roomie (one doll with 15 accessory pieces) is $35 to $40; Delux Roomie (one doll with 30 pieces, a hat and a hairpiece) is $55 to $60. Shelly Adventures, 55 Mercer St., New York, N.Y. 10013; (800) 645-6921.

* Professional sports teams offer almost everything with individual logos. But Pro Bear, “the first-ever officially licensed teddy bear of professional sports,” is sanctioned by the NBA, the NFL, the NHL and Major League Baseball. You can order this bear with any team logo. Pro Bear is an OK stuffed bear, but with a price tag of $80, he ought to be able to jump like Jordan, pass like Marino, score like Gretsky and bat like Bonds. Meadowlanders Inc.; (800) PRO-BEAR.