"No turning chain" double crochet is something I've heard about from time to time, but never tried until recently. It's really not difficult once you've done it a time or two, and it does seem to blend in with the rest of my stitches better than a turning chain does.
Here's the video I learned from:
This is one technique I'll actually use, unlike that seamless join thing that requires you to cut your yarn at the end of every round. That has always seemed like just way more work than it's worth, unless you're going to be cutting the yarn every round, anyway. But then again, I'm a little lazy about that sort of thing, so... (Have no idea what I'm talking about? Here's one photo tutorial.)