Finding Nemo - This doesn't have to be an expensive project. Perhaps purchase a few Finding Nemo ornaments and add your own touches — ribbons, netting, etc. — to complete the theme. You can even check toy departments and stores for small Finding Nemo toys, then add greenery, ribbons and glitter to make your own ornaments.
Little Mermaid - Besides the Little Mermaid herself, this could be a fun theme. Remember that Ariel spent a lot of time in front of the mirror, so add a few doll-sized mirrors and combs or brushes (the kind you often find as birthday party favors) tied with pretty ribbon. Ariel was also collected "treasures" — things she found interesting that were discarded in the sea by humans. So, small treasure chests full of jewels and odd items would also be appropriate.
