The Purl Bee has a tutorial on how to make a duplicate stitch, a great way to add some patterns to your knitting without the fuss of intarsia.
From the site:
Duplicate Stitch, or Swiss Darning as it is sometimes called, is a really simple way to add personality to a project. The basic concept of Duplicate Stitch is in its name. You sew over your finished knitting with a contrast color, “duplicating” the original knit stitches. It’s much easier than fair-isling or intarsia.
To find out how to do the duplicate stitch, visit The Purl Bee. – Link.