I posted a link to a pattern for leaf chains earlier. (go here to find it) http://crochetedsass.blogspot.com/2009/07/i-found-pattern-for-leaves-leaf-chains.html
Then Cindy (cvansluys on scs) mentioned doing them in fall colors so I did a few different chains. The top one is done with different crochet threads (size 10) changing colors after each leaf. The bottom 2 are done with varigated floss. I think they're both cool effects.
Here is a close up of the chains.