Let's face it, cords come in handy. Bag straps, amigurumi appendages, fringe, top knots, the random tentacle or twenty...whatever you're making could use one or two.

Of course, this is a relatively recent discovery of mine. In 30 years of crochet, I never much thought about them until I started knitting earlier this year. Maybe I was just crocheting the wrong things, but you can't knit for long without running amok with i-cord. As with many things knit, midway through struggling with my first one, the needles went flying across the room when I lunged for my hooks and I had miles of i-cord in what seemed like seconds. Here's what I did:

[1]

Make the ever-present slip-knot and chain two. Plant 3 or 4 or 5 sc into that first chain space. Work 1 sc into each of those, no need to sl rounds together, just spiral around...on and on and on until it's as long as you like or need. If you're going to attach the end to something, just cut your yarn, leaving a nice long, sewing tail and pull it through that last stitch. If you want to close the end of the tube, work 2 or 3 sc together until it is, then cut yarn and pull through to secure.
Voila, i-cord. (edited to add some mediocre pictures that really don't clarify anything. you're basically just working a long tube...a teeny tube. Like a 3 (or 4 or 5 or whatever) sc circle you never work increases on.)

Some ideas:

Braid several together for bag straps (that don't stretch as much as knit cord either...and make a wonderful, thick felted strap too)

Worked a bit bigger, makes a great snake

Make a few inches of cord, then start increasing into a hat, which now has a top-knot....who-ville style.

Work at the corners of pillow covers to make chair ties...or heck, tie down the bottom corners of your comforter and your toes will never be chilly again.