This is one of the reasons I find knitting so soothing: When I'm experiencing stressful mental noise, I can pick up the needles and put all my attention on "knit, knit, knit, knit, purl, purl, purl" (quite literally - I often subvocalize the stitches as I go) while experiencing the pleasurable sensation of the yarn running through my fingers. Before long I can literally feel the stress draining out of me and whatever was bothering me receding into something like its proper place. And unlike straight meditation, I wind up with something pretty when I'm done.

I've seen references to studies suggesting that knitting and other pleasantly repetitive, quiet activities can lower one's blood pressure, and that doesn't surprise me a bit.