I've tried out quite a few different pens with Faux Embroidery techniques and will continue to test them. I thought I'd give them their own post, so I can refer back here as I post more faux embroidery projects in the future.
Here's a sample of how my three favorites performed side-by-side. This is demonstrated using Twin Stitchers "Get Crackin" pattern available here (or you can download it free this month (April 2011) on the Twin Stitchers sidebar.) The colored in circles were done using the brush tip of the colored version of the Marvy Uchida markers. The writing was done using the ball tip of the colored markers. (Click on picture for larger view.)