Well, the stuff that I've created so far:

- A level with the Windstorm Fortress tileset. Water rises as you progress. Bilsy is the boss, although I'll probably change this later.
- The infamous Bubba pit level, where you fight on a number of collapsing platforms. Uses the Pezrock tileset, but I'll probably change this later.
- An idea for a skyscraper level, but I haven't started to make this yet.
- An enemy-infested swamp level. Three guesses what tileset this uses.

And that's about it for what I've made so far, because I'm not going to spoil the secrets. ;(

EDIT: If I have enough time, I'll also make alternate level-paths for Jazz and Spaz.