Step 1: See which size crochet hook matches your knitting needles. I cheat and look at the back of the yarn, but I'm sure you could shove your hook through a needle-size-board thinger.
Step 2: Chain one LESS than the number you're supposed to cast on (here, I've chained 12 for a cast on of 13)
Step 3: Here's the mind blowing part: Start from your first chain, and simply pick up the top loop of each chain! It's that simple!
Step 4: Threading on more chains. If you notice, I'm not twisting them....put the needle in from the back and lift each one onto your needle
Another view of step 4
Step 5: When all chains are on, simply slip that last loop of your crochet hook and onto your needle (that's why you chain one less than the number you're supposed to cast on)
Slips right on
Voila!! Cast on, super quick and super easy!
I figured this out while working on a hat for Gitchell's...I had to take the first two rows out more times than I'd care to admit. But, while taking out the cast on stitches (oh, how that hurt!), I realized that I was really taking out a crochet chain. And, if it came off that way, then surely it could go on. And I can now cast on bunches of stitches super quick. So, the only thing I'm left hating in knitting is that dad-blasted plastic string between circular needles......
Note: I know there's the "twist the yarn around your hand" method, but that always ended up horribly twisted for me. This way, not so much.