meandering ribbon we have done in Week 30. There is a good tutorial for basic chain stitch in Sharon B's Dictionary of Stitches here.
This sample is from an antique piece of embroidery and was used to attach a piece of embroidered gauze to a silk dresser scarf. After fifty plus years it is still serving this purpose very well. So, this technique would be very appropriate for a seam that is in need of stability from it's treatment instead of embellishment alone. By meandering back and forth across the seam in a random manner (much like stippling in traditional quilting) with a line of chain stitch, you can do a lot to strengthen the fabric join. Using a variegated thread as in the sample photo adds more interest and beauty to the stitching.
I hope you'll enjoy this week's challenge and I'm looking forward to seeing how you use this in a seam treatment. Have fun!