A movie is a great idea. Michaela loves Ice Age 1 & 2 I'm really looking forward to taking her to Ice Age 3.
CuriousG got Michaela a crayola colour wonder colouring in book for her 3rd birthday and that was a huge hit! If you go for that be sure to get the ones for age 3+
Another thing that my 3yo loves is pretty necklaces, hairclips and ties, tiara's, wands etc. You could get her a music jewellery box and fill it with costume jewellery from $2 shop or chemist.