This is actually the second ACEO I have done (the first one was blah). I used textured cardstock, a rubber stamp, ink, a flower sequin, and Swarovski crystals. The image of the girl is from an ad in a magazine I have from 1969 (I love the ads from that era!) - I did *not* draw her! .. I'm not that good. :)
So what do you do with these things? A lot of people collect them. I'm just starting my own collection, and you can buy baseball card binder inserts and keep them all in a binder. Or, there are picture frames this size that you can use to display them individually or in groups. You can also make a collage out of several of them and have it framed that way (which looks really cool).