I can think of a couple very exotic snails but generally, it's probably not worth it since the behavior of most snails is pretty much the same (with some divisions of commonly sold sandsifters, algea eaters, whelks, etc) and anything like them will usually have coraline covering their shell.
There is a particular cold water species that has a very colorful rainbow like shell (I forget what they're called) but like I said, it's pretty but will be covered in coraline anyway.
Cone snails are pretty extreme too, they're the blue ring octopus of snails, but I never met anybody who's had one. Venomous snails are the one division you're not going to commonly see in the hobby, but I think that's for good reason..