A stacker...
[img]http://multimedia.mmm.com/mws/mediawebserver.dyn?6666660Zjcf6lVs6EVs666XdTc7rrrrQ-[/img]

This one is 3M, but others make them too.
They hold snug enough for being fairly undisturbed in a wall, but loose enough that a good tug will pull a cable free of one if set up to do so.

Like the job I was on today, a "Designer" is running it. (Notorious for frequent changes ...) So I had a guy staple to about a foot from the box, then add a small loop of slack above or below, then into a stacker for the final support of the <12" of cable that would continue to the boxes.

I also use these boxes for just about everything.... (Several local supply houses have them as the same price as a regular nail-on.)
[Linked Image from carlon.com]
The screw on the side allows the box to be adjusted for depth, but also allows the box to be removed as well. So you can easily reach in the wall and pull up more wire too.

[This message has been edited by e57 (edited 05-11-2006).]

Mark Heller
"Well - I oughta....." -Jackie Gleason