Those who already know this, ignore it, of course. But I've been working with Blender for three years and never knew this until now.
My friend the mysterious Lord Enigmatic just shared this incredibly useful little tip with me. Normally if I want to select an edge loop (that's a circle of vertices, something you need to do a lot when modeling clothes or armor) I would press ctrl+e and select from the menu that comes up. It's faster and easier to select one vert and press alt+right click. It takes a little bit to get the hang of it, since it chooses which vert loop to select based on which direction you click, but it's VERY worth it.
And you know why?
It works in the UV screen too.
I cannot even DESCRIBE how useful this is. It has cut my UV mapping time in half. The reason is that whenever you model something long and twisty, like a strap or a belt or a vine, you can't auto UV map it without it looking screwy (even with a seam up one side created by selecting a vert loop with either method). Before I would have to individually select every individual vertex in that line of 100 or so before I could use w, 2 to haul them into a straight line. Now I can just alt+right click and there it is.
I am SO geeked out about this, I had to share it with everyone. I'll be posting it on other forums I frequent as well.
EDIT MUCH LATER: I just got this message from Vince here at the forum. He suggested consolidating the relevant info, and it seemed like a good idea to me. It will be added at the end as well.