I’m a fan of Manfrotto tripods, and a good lightweight model is the 190XB. B&H Photo sells it in a kit with a Manfrotto 496 compact ball head for $183. It weighs just over four pounds, which is about average for a lightweight tripod. Even better, it'll support most any load you put on it—for example, using a DSLR with a long telephoto lens.
A comparable tripod is the Vanguard Alta, using a 264AO head. It also weighs about four pounds, supports 12 to 14 pounds, and sells for $180.
If you really want to go lightweight, though, you'll need carbon fiber. The Smith-Victor CF1 with a BH2 head, for instance, weighs just over two pounds and supports five pounds—enough for a small DSLR or a video camera. And at $170, it's reasonably priced.
The Oben CC-2300 (with a BA-O ball kit) is another carbon option. At three pounds it’s beefier than the CF1, and it will support ten pounds of equipment. On the other hand, at $289 it’s a bit dear.
But the best backpacking tripod, in my experience, is the Leica Tabletop Tripod. It's been around for years, and I've found it to be an extremely sturdy, compact device. It’s short, but you can always find something to perch it on. For $110, it's cheaper than anything else on the list.