its called the reshape tool
http://www.creativecow.net/articles/zwa ... index.html
i agree, morphing yourself into a sheep isn't very exciting, but it will show you how to use the tool.
the reshape tool has some drawbacks, however. You cannont make "control splines". That won't make sense to you until you've done a few morphs and start realizing the amount of control you need for a super high quality morph. But, for the most part, Reshape gets the job done fine.
twixtor is another one, sorta the standard tool right now for this type of effect.
I don't like twixtor at all. I used it many, many, many times on movies, and more often than not it makes more cleanup work than you can imagine. It does work, but I hate it.
Elastic Reality, which is LONG discontinued, is by far and away the best morphing/warping tool out there. It's awesome.