I see a couple of threads about 3-year-olds and all their ::ahem:: charms, so I wanted to recommend
this book which has been helpful in understanding what is up with DD. I pull it out whenever I am reaching that point of wondering what in the world is wrong with her or why I'm feeling like such a failure...there are no magic answers in here but it is a good reminder that it is all normal. Also read
this review from askmoxie.com for an overview.
Re: s/o 3-year-old behavior