I'm taking a gauge class in a few weeks, and the instructor asked us to come with four 5X5" swatches in:

Garter
Stockinette
Lace
Cable

I have garter and stockinette, but I've never done a gauge swatch in a lace pattern or a cable pattern before. Does anyone know what pattern or stitch combination would be appropriate in this case?

You're going to have to go to some stitch pattern collections. You can find some at www.knittingfool.com, www.knittingpatterncentral.com/directory/stitches.php www.knittingonthenet.com/stitches.htm