WEIGHTY SUBJECT. These Chinese exercise balls are said to stimulate circulation, relax muscles and fight arthritis and hypertension. Manipulate the hollow balls with the thumb and fingers (instructions -- in English -- elaborate) to experience a sense of well-being the Chinese have known for 800 years. The two chrome or brass plated balls emit chimelike sounds when turned, measure 1.8 or 2 inches in diameter, and come plain or engraved (a phoenix on one, a dragon on the other).

* Chinese exercise balls. $31.95 to $34.95 a pair, plus $2.95 postage and handling. MMJV Enterprises, Box 11050, Arlington, Va. 22210. For information, 525-0166; charge orders, 1-800/628-2828 ex. 999.

CANDID CAMERA. No matter how vigilant you are, you can't know what the kids are up to every minute. But you can keep an electronic eye on Baby with this book-size video camera. So while Mom is hanging wallpaper in the downstairs powder room and Dad is in the garage changing the oil on his old Stingray, they can look up every once in a while to make sure that Baby is still asleep. (When Baby grows up, the fun really begins as you train the camera's eye on the teen-ager coming home from her first date, your mother-in-law coming up the walk . . .)

Sony monitor system. $499. The Sharper Image, The Shops at National Place, 14th and F streets. 626-6340.

COLOR THERAPY. Stop chasing rainbows; wrap yourself up in one. This hand-painted silk import can make you feel like it's April in Paris even if you're here in March. The colors go with practically everything and the 9-by-50-inch scarf can decorate your home when it's not warding off chills or gusty winds. It would be almost impossible to wear it and not smile the whole day through.

Rainbow scarf. $22.50, including shipping and handling. Philip Cary Ltd., Box 261006, Denver, Colo. 80226. 303/744-1403.

JOIN THE CLUB. Using the idea of peer pressure with a positive twist, "Just Say No" is helping to fight drug abuse among children. The organization's clubs are popping up all over the country. Geared to children from 7 to 14, local clubs hold drug-free parties, publish newsletters, decorate school and community bulletin boards and proclaim their beliefs by wearing club buttons and T-shirts. "Walks Against Drug Abuse" are scheduled for May 22 if you want to join the throng.

Just Say No clubs. For more information, call Jean McMillan, Pacific Institute for Research and Evaluation, Bethesda office. 986-0301 or 800/258-2766.