We have been reading My Father's Dragon and today we finished the final book, The Dragons of Blueland. These short chapter books are such a fun read aloud and lend themselves very easily to making mental images.
This poem by Jack Prelutsky"My Neighbor's Dog is Purple" is from Deanna Jump's blog and I love the idea that she broke the poem into 2 parts so that students could really see how their mental images change through the course of reading a text.
Green Giant Poem - Mrs. Williamson at Welcome to Room 36 has some FANTASTIC resources for teaching mental images using the poem Green Giant. She even has a copy of the poem you can use in a pocket chart.