Playful: I think this is a very loosely defined category. Subject matter can be playful, as in the following example:
or, visual style can be playful, as in the following examples:
Pop Art: Using the anonymous, everyday, standardized, and banal iconography in American life, as comic strips, billboards, commercial products, and celebrity images.
A few excellent examples of pop art scrapping:
Punk: This was a tough one. In my opinion, punk scrapping should be edgy, both the photos and the paper/embellishments used. The subject matter should suit the design. I found it very difficult to locate layouts that I really felt fit this description, but here are a few:
I think the first two are the closest to what I would truly consider "punk" but I think there is a bit left to be desired still - I'm going to attempt to create what I would consider a true punk layout in the next few weeks to see if it is even possible to apply this medium fully to scrapping.