* In rural northern Nigeria, there are no refrigerators. Most people don't even have electricity. So perishable food must be eaten immediately, or it will go to waste. Mohammed Bah Abba, a local teacher, has developed an ingenious solution: the Pot-in-Pot Preservation Cooling System. A small earthenware pot is placed inside a larger one, and the space between the two is filled with moist sand. The inner pot is filled with fruit, vegetables or soft drinks; a wet cloth covers the whole thing. As water in the sand evaporates through the surface of the outer pot, it carries heat, drawing it away from the inner core. Eggplants stay fresh for 27 days, instead of the usual three. Tomatoes and peppers last for up to three weeks. A recipient of the Rolex Award for Enterprise, Abba, 37, who hails from a family of potmakers, is using his $75,000 award to make the invention available throughout Nigeria. He has already sold 12,000.

* They are every gardener's nightmare: big, slimy slugs that eat holes in lettuce leaves and gouge craters in tomatoes. Now Ian Kelly, a computer scientist at the California Institute of Technology, has developed a robotic slug catcher that not only identifies and eliminates slugs but could eventually power itself with its victims' bodies. Here's how the Slugbot works: a lawn mower size machine with a long arm shines red light on the ground to identify a shiny, sluglike object, then analyzes its shape. When it finds a slug, it picks it up and drops it in a hopper. Bacteria inside the robot eat the slimy critters—a process that releases electrons that can be captured and, in theory, keep the bot's batteries perpetually charged. Kelly says he has perfected the slug-identification-and-retrieval system but estimates that it will be several years before the slugbot is ready for market. Biggest hurdle: getting the robot to convert those captured mollusks into usable energy. While the concept of microbial fuel cells has worked in laboratory tests, applying it to slugs turns out to be a sticky proposition.

* Cell phones are supposed to make our lives easier. So why do wireless companies keep packing them with pricey extras—like color screens, Web browsers, games and e-mail—that most people don't need? Now several companies are developing stripped-down, single-use models targeted for casual users who just want to take a cell phone on vacation or stash one with their emergency flashlight. One of the first to market will be the Hop-On Wireless (shown here) priced at $30 for 30 min. of talk time. To keep costs down, the device (about the size of a deck of cards) contains only a quarter of the components found in a typical cell phone. It doesn't take incoming calls, and there's no keypad or display. Instead, users plug in an earpiece (included) and speak the number aloud; voice-recognition technology converts the sounds into digits and places the call. To activate the phone, users simply push the green call button. Color-coded lights indicate when the 30 min. of prepaid talk time is running low (yellow) or out (red). The lithium-ion batteries will last for up to two years, so your minutes will probably run out before your batteries do.

* Ever notice how ordinary light bulbs cast a yellowish glow around your rooms? The new GE Reveal bulbs produce a crisper, whiter light that is much closer to natural sunlight and makes colors look brighter. Ideal for kitchens or work areas around the home, the powder-blue bulbs are no more expensive than regular ones. The secret ingredient is neodymium, a rare earth element that is baked into the glass to help filter out the usual yellow hue.

* Forget the down jacket, the long underwear and the extra-thick scarf. Designed for extreme cold, the North Face MET5 jacket can keep you warm all by itself, thanks to a network of microscopic, waterproof heating elements woven into the fabric. Working a control unit stashed near the chest, you can dial the heat up to 114šF. Small lithium-ion batteries keep the juice flowing for up to five hours.

* Tired of having your cell-phone battery go dead just when you need it most? FreeCharge is a half-pound, hand-cranked generator that you can attach to your cell phone and turn for 30 sec. to generate enough juice for five minutes of talk time. The first version will work on most Motorola phones; the next ones will power other makers' phones. This is the third in a series of windup electronic devices originally designed for use in developing nations. The first two—the Freeplay radio and flashlight—have been surprise hits in the U.S.