Recently we've seen the "meta" open up to a degree. While it's still common to see an AD carry, support, jungler, AP carry, and tanky DPS, the champions and their roles have been broadened past just "top tier" champions. It is now acceptable to have an AP top and an AP mid, for example.
Now, in addition to more champion options, we've begun to see teams start to synergize their team compositions for a certain playstyle. For example, I often see CLG.na go with a "frost comp", as they call it. This includes Janna, Ashe, and Sejuani in order to slow or freeze the enemies so they they can catch them out of position. The other two champions on their team are usually designed to burst down those caught champions that are caught, making an easy 5v4 win later.
So, in reference to this "frost comp" and the fairly common "poke comp" and "aoe comp", what are some other champion compositions you have seen? What playstyles are neccessary and what method is required for it (i.e. catching someone in the "frost comp")? Does it seem to be fairly successful or just fun?