The best place I suggest you pop over to is the Slip project, where they have some great suggested patterns.
Even more exciting, is I have the Slip project! It will be installed at the New Dowse reception desk on Wednesday, 12 May, around the same time as It's a Tree! goes live.
I've been knitting my heart out all weekend making leaves and other bits and pieces for the tree. My 11 year old brother is going to make a needle felted creature, and there are photos popping up all over Ravelry of clever creations for the installation.
I can't wait!