I'm talking about Heavyhands.

Dr. Len Schwartz, Creator of Heavyhands, in his 80s.
Heavyhands is a fusion of weightlifting and aerobics that improves both strength and endurance. It's easier on the joints than running, yet works the entire body, can be done in a small space in front of the TV or in the great outdoors and uses inexpensive equipment (light hex or padded dumbbells ranging from 1-10lbs with a few exercises calling for slightly heavier, 20-40 lb. dumbbells). It spreads the cardiovascular load across your body and allows you to burn more calories at any given level of perceived effort (meaning, it SEEMS easier to burn MORE calories, as your whole body is participating in the effort). For bigger guys like myself (I'm 220 lbs right now, down from a high of 270+) it allows me to get a pretty tough aerobic workout in without the pounding on the joints that running entails.
In its simplest form, heavyhands is just walking while holding weights and using an exaggerated "biceps pump" maneuver. Just this simple move can really boost the calorie burn of your walks. To vary the difficulty, you can vary your pump height, pace, or walking speed. There are, of course, many other maneuvers to try, from overhead presses, shadow-boxing, and double ski-poling (think of the maneuver you use with ski poles to propel yourself forward). All you really need to get started is a couple of 1-5 lb weights and a route to walk or room to march in place.
So what happened? If this system was so darn good, cheap, easy to do anywhere, and effective, why isn't it still with the masses? I can think of a few reasons.
Dr. Schwartz, the creator of the system says (at Clarence Bass' webpage) "Even huge weights don't evoke much aerobic work when hanging inertly... You have to act boldly." That means you actually have to pump the damn weights, high, fast, or both. This had two effects: one, to get a good workout, some people really pumped the weights, and then realized, "hey, this is still hard," and stopped. Runners found that the weights "threw them off their stride," meaning, of course, that even though they were getting a better work out, their egos couldn't get over the fact that they had to go slower. The second effect was that some people just carried the weights around, then found, "Hey, this doesn't work." And these people went back to just walking. You've got to pump the weights high to get the effect you're looking for.
Two: it looks funny. Though I imagine jogging looked funny at first to people as well. I just try to ignore the funny looks I get, pumping weights, but some people aren't as able to ignore it. To those people, I suggest working out in front of the TV.
Three: ironically, I think Heavyhands kind of killed itself because there was so little equipment to buy. Besides a couple of books (Heavyhands: The Ultimate Exercise System
My recommendation? Give 'em a try. In the meantime, you can do a bit more reading about heavyhands at Clarence Bass' website here and here or at the heavyhands blog (which looks defunct but has a good archive). If you need more info, grab the books. They're packed with good information.
I've got more on heavyhands coming up, plus another post on home gyms in apartments, plus the rest of the pulse series, and a mnemonics series, plus some other surprises. Stay tuned.