Here are a few of the bulletin boards we pulled together after scouring the internet for ideas and brainstorming:
At our local Meijer store, I found these fantastic Crystal Effect Window Markers by Crayola and they made the most awesome stars on our windows. You draw whatever design you want on the window and then wait... within seconds the liquid marker begins to "crystalize". It is so cool! I had a fun drawing stars, but I think I actually enjoyed more watching them dry. Try mixing colors too! I got some neat results!