Two more stars: I got 100 coins in Lethal Lava Land (clearing the world) and I got In the Igloo in Snowman Land.

The 100 coin one for Lethal Lava Land presented a few problems. However, I earlier decided I could easily get 20 coins from inside the volcano (and there are a few more than that, if needed), so I only needed 80 from outside. I ended up getting 91 from outside. And there were still about 5 or 6 more I couldn't get, because they were right on the lava.

I'm sure there must be a turtle shell in that stage somewhere (there's a clue for one), but I haven't found it.