Dipping is when you take a basecoated miniature and literally dip it in stain (or ink, or magic sauce, etc.).
I have no pictures, alas; but two people in my group have used dipping with reasonable results. One dipped about 50 zombies, the other dipped his Nurgle marine army. Both turned out well. They used very bright greens and browns as the base colors (like, scorpion green and bubonic brown), and Minwax satin polyeurethane varnish in a medium shade- maple I think- a wood stain. And they said the key was to dip the figure, then sling it, sling it, sir, as hard as you could, to shake off as much stain as possible. Then set it aside and leave it alone for a couple of days until it is dry.
Another gave it a try, but used a very dark stain, and apparently did not sling the figures with enough vigor... now he says he has African zombies.
Great technique if you have lots of the same style figure to paint (like for tyranids or skeletons), not so good for other things. I wouldn't try it with marines unless you were going for a dingy, dirty look. Worked great on plaguebearers.