Trying to describe what a web design will look like or what we're about to change with a layout is a challenge over the phone, especially with the limits of technical jargon. The best way to communicate tricky changes is to show them.
I know there are a million collaboration tools like WebEx and Genesys out there (heck, we even set people up with Unyte for webinars), but for a quick show-and-tell, I love Twiddla.
It's free and lets you mark up websites, graphics, photos or just blank canvases. And there's no annoying set-up. It's simply worked for everyone I've worked on it with, no matter what archaic machines they have.
Click "Try it now in the sandbox" to see how it works; no need to log in.