Mixing things up a little with Paint Pens

I've been obsessed with acrylic paint pens lately...I've discovered Montana and Liquitex artists' paint pens, and have been using them for everything I can think of in a painting: line, of course, to accent or create focal points, and misty smudges to create an atmosphere or lay a bit of a pale background for some later washes, drips of acrylic ink, or strokes with watercolor brush pens.