I love cables! I think they're one of the easiest techniques to master, and yet they yield spectacular results. Nothing is quite as disappointing as working for hours on a complicated technique, only to have the piece look approximately the same as it would have if done simply. With cables, this is never a problem! They turn any plain project into a beautiful piece that's interesting to knit but not (usually) impossibly intricate. Take a look at the Cabled Baby Sweater that I made last fall to learn more about adding a cable to a simple project.
You can knit a cable onto anything you're making, so if you've made mostly scarves, try a cabled scarf pattern. If you're into hats or sweaters or socks or ponchos or afghans or wrist-warmers, there are cabled projects for you! And after you've tried some simpler things, try making or even designing your own Aran sweater, combining multiple cable patterns in unique configurations - and Arans are great gifts for hard-to-knit-for men.
Cables are created by knitting stitches out of order on a purled background; you skip two or more stitches on your right needle and knit some number from further down, then you go back and knit the stitches you've skipped. Ordinarily, you'll use a cable needle to hold the skipped stitches, but it is also possible to cable with just your two regular needles (take a look at Carole Wulster's book
Cable Needle Freedom to learn more about this great time-saving technique).
Yarn: You can use a wide variety of yarns for cabling; the most important factor in choosing for a cabled project is definition. Very fuzzy or novelty yarns won't show a cable pattern well; the best yarns for cables have relatively little fuzz