We made these posters on different ecosystems. The students choose vocabulary words to go around the border of the picture. Each word included around the frame had to be drawn inside the picture. They had to include abiotic (never living) and biotic (living or once living) items in their poster. They turned out great! Here is a link to the FREE directions and pics.
Smart Chick Teacher's Blog 
I just found your blog through the Secondary Solutions Linky Party! I absolutely love it and am adding your to my reader! This is a really great idea– I may have to steal it to use with my kids next unit 🙂
Kate
http://tothesquareinch.wordpress.com/