Well, neither the Powershot series (Canon's point-and-shoot cameras) nor, say, the Rebel T1i (which is what I want for Christmas) are particularly heavy, so most lightweight tripods will work well. You sure you even want to lug a tripod? They can be handy for night shots and the like, but will simply add to your baggage.
My pick? The Leica Table Tripod ($109 without ball head). I've had one for...well, a long time. A totally bulletproof, packable, compact tripod. As the name implies, it's a tabletop model—only six inches tall or so. But it's remarkably handy as you usually can find something to put it on if you need to find some height. A table, for instance! The only cautionary note is that the thing WILL show up as a handgun on X-rays. I've had my bag rifled more than once as a result of carrying it.
Otherwise, look at one of several standard-size, lightweight tripods. Manfrotto makes a number of excellent tripods. Typical of their lightweight line is the 7321YB M-Y ($118). It's a full-size tripod with a three-way head that weighs a reasonable 3.6 pounds. It's plenty sturdy enough for an SLR-type camera with a mid-sized zoom or telephoto.
A little more compact tripod would be the Slik Sprint Pro II GM ($89). It folds down to 19 inches in length, and weighs a bit over two pounds, yet extends to just over five feet. It has an all-metal ball head that makes it easy to pan and set the camera precisely. It has three-section legs, and the ability to get a camera lens within six six or so of objects on the ground, which is more useful than you might think.
Or you can just say "damn the budget," and get a carbon-fiber tripod. Something like the Gitzo GT2531 ($722). All the strength of a tripod weighing six pounds or more, yet tips the scales at 3.18 pounds. Telescopes down to 25 inches. Very nice tripod.