Slip stitch patterns create a lot of visual intrigue, because stitch lengths are not all the same. They also have the added bonus (or curse, depending on what you're looking for) of pulling the fabric together, resulting in a heavier, thicker fabric.

My favourite slip stitch pattern goes something like this:
CO 2n+1 st
*p1*
*k1 s1* k1
*k1 ybf s1 yfb* k1
*k1*

This pattern is half stockingette stitch, with slipped stitches spanning three rows and a great square pattern on the back.