Some of the Kenmores use cams that extend the decorative stitch possibliities, and some even have "reverse" type stitches so that your can even sew little duckes, greek key, etc.. I have one such machine in my personal set of "keeper" machines. They aren't as "collectable" as the Singers, so they tend to sell for less.
I have a slew of
sewing machine reveiws on my blog, you might fnd them helpful. If you are interested in learning more about the Singer slant-o-matics as mentioned by ksrunt, be sure to check out the review I have on those specifically.
Slant-o-matic reviewEnjoy your "hunt"!