I like wavy lines made with the walking foot. It is very easy; you simply pull slightly on the quilt right and left as you sew. Here is a link to Google images that show some of the possibilities:
https://www.google.com/search?q=wavy...UIBigB#imgrc=_
And here are links to some tutorials:
http://www.bijoulovelydesigns.com/20...-tutorial.html
http://betteroffthread.com/2013/03/0...ting-tutorial/