I use this when I introduce functions in pre-calculus, based on a popular social website. I present these as the 12 basic graphs from which we will be launching our study over the year. Some they have already seen in previous classes, which I call their friends. The new ones I ask them to be-friend. For each, I name the function verbally (i.e. the squaring function) and with an equation. Then, to make it fun, I give each function a personality.
Of course, you can be more creative with your personalities. Alternately, the students can make their own. It really helps them remember throughout the year. I often refer to functionbook in my lessons and homework. The students think it is really fun as it meets them in a familiar forum.