My wife just found this, came out today: Coaster iSim [Alternate AppShopper link] It's a total rip of Air Coaster 3D, but with a contrived name and lame use of the "i" meme, and minus the panoramic backdrops, music, etc. It also features a 3D mode, but it uses the cross-eyed stereographic method used in MagicEye images. (Yay! Migraines for everyone! Except Silent Bob.) Looks like a cheap attempt to cash in on Ziconic's success.
I am the dev for AirCoaster and I have this app! It's actually been around for a while, but it used to be called something else, like Coaster 3D Stereograph or something like that. I don't want to say anything about the competition -- you guys can read the reviews for yourselves -- but the one thing that upsets me the most is that they have a 2.5 star rating, and no matter how many features I add to AirCoaster, it still ends up with 3/3.5 stars. Oh well.