It's also a great way to add a contrast colour edge to any garment or accessory - just don't unzip the cast-on edge. I also love it for casting on lots of stitches, for instance, for a cowl or infinity scarf - no running out of the tail-end of the yarn. Again, just don't unzip the cast-on.
Use either, two different balls of yarn to cast on, or, both ends of the same ball, cutting the 'tail' end once enough stitches have been cast on.
It does leave you with 2 extra yarn tails to weave in. But for me, I'd rather that than rip out 160 cast on stitches and do them all again.