Reaching Into a Mixed Bag of New Products for the Frequent Traveler : Marketing: The latest items designed to make life easier on the road range from bath oils that combat jet lag to a portable water purifier.

What do Princess Diana’s bath oils, insurance for frequent-flier miles, computerized Civil War records and hotel voice mail have in common? They’re among the diverse array of new products and ideas designed to make life easier or more interesting for frequent travelers.

The fragrant bath oils are being touted by Air New Zealand as an aid against jet lag. They come in an After Flight Regulator Kit that contains two small vials labeled “Awake” and “Asleep”--distributed free to the airline’s first- and business-class passengers (and for a fee to coach passengers). After a long flight, you add a few drops of the oil to your bath or shower--Awake to stimulate the senses and keep you alert for an important business meeting, Asleep to soothe the senses and help you sleep after crossing numerous time zones.

The oils certainly are the most exotic of new products, services and ideas aimed at frequent travelers in recent months.

Some of what’s new:

--Safe drinking water: Impure water is a health hazard in many Third World nations and remote areas of the world. What do you do if bottled water or other bottled drinks aren’t available, and you have no way of boiling water for a cup a tea? Recovery Engineering, a Minneapolis firm, has developed a small, easily packed water purifier that it claims can produce a cup of safe, disease-free drinking water in seconds.

The portable system, called PUR Traveler, was tested by the University of Arizona’s department of microbiology and immunology, according to Recovery Engineering, and was found to meet federal standards for eliminating disease-causing cysts, bacteria and viruses in drinking water.

The purifier, which comes equipped with a cup, is about seven inches long and weighs 12 ounces, which makes it slightly larger than a soda pop can. To operate the device, you pour water into the top, pull up on the piston pump and then depress the plunger for a cup of water.

The cost is $49.95, and replacement purification cartridges, good for 100 gallons of purified water, are $19.95. The firm also designs heavy-duty water-purification and desalination systems for the military as well as for sailing vessels and campers. The PUR Traveler is sold in camping goods and outdoors stores, or it can be ordered by mail: (800) 845-7873.

--Insuring frequent-flier miles: Given the uncertain financial health of some U.S. airlines, many frequent fliers are worried that they could lose the frequent-flier mileage credits they have earned if their carrier goes out of business. Some passengers have built up hundreds of thousands of miles of credits.

To prevent such losses, a Colorado Springs firm last month began selling frequent-flier insurance called AwardGuard. Subscribers can insure all their mileage credits on all U.S. airlines except Pan American at an annual rate of $79. The insurance, backed by Lloyds of London and other insurance companies, is being sold by Frequent, the monthly newsletter for frequent fliers published and edited by Randy Petersen.

For information about Award-Guard: Frequent, 4715-C, Town Center Drive, Colorado Springs, Colo. 80916, (800) 487-8893.

--Seeking Civil War roots: The National Park Service has launched a three-year project to computerize the Civil War records of 3.5 million Civil War veterans, Union and Confederate. Beginning in 1994, visitors to the nation’s 28 Civil War battlefield parks will be able to view on a computer screen the Civil War records of their ancestors.

The data is coming from microfilm copies of 5.5 million handwritten records stored at the National Archives, covering 7,500 regiments and 10,500 battles or skirmishes. The information they contain was collected on a regular basis by military officials throughout the war, from 1861-65.

--Tax rebate trend? To reduce the high cost of travel to London, the luxurious St. James Court Hotel is rebating Great Britain’s value-added tax on room rates. Normally, rebates on the tax, which amounts to 17.5%, are applied only to items foreign visitors take from the country.

The refund is no small sum. The daily rate at the hotel, located next to Buckingham Palace, is about $360 a night, which puts the value-added tax at about $63. Through Oct. 31, however, the hotel is offering two nights for the price of one. For more information: (800) 458-8825.

--Phone savings abroad: Unlike other international telephone charge cards, the new Executive TeleCard allows callers to phone within or between foreign countries by direct dial without paying the substantial surcharges imposed by most hotels.

The cost of an Executive TeleCard is $50 a year, and you will be assigned a personal identification number. Phone calls are billed to a major credit card. For information: Executive TeleCard Ltd., Twinbrook Metro Plaza, 12300 Twinbrook Parkway, Suite 625, Rockville, Md. 20852, (800) 723-3932.

--Getting the message: Whether you are traveling for business or pleasure, getting your messages is important. Too often, the hotel industry fails miserably in providing this service. But help is on its way. At least one new hotel in New York City, the 460-room Embassy Suites on Times Square, has installed a voice-mail system, and other hotels are expected to do the same in the future.

Located in the Theater District, the year-old hotel charges $169 to $209 for a suite for four with breakfast on weekends, $189 to $249 on weekdays. For information: (212) 719-1600.