With the purchase of a variety of cartridges you can cut out thousands of shapes and letters. Now the cartridges can be pretty expensive, but if you look for clearance sales or on ebay, you can get them pretty cheap.
I use the Cricut for bulletin boards and other signs that are needed around school. I can change the size of whatever I am cutting out from 1/4 of an inch to 5 1/2 inches. I have the smallest Cricut, but with the largest one, you can make pieces up to 23 1/2 inches. Here are some of the things I have created with the Cricut for the art show and bulletin board outside of my room. I used the snowflakes to make the border for the bulleting board.