There are so many varieties of rats out there, that petstores haven't gotten ahold of and ruined yet (like the hairless).
By carefully screening potential adopters, and requiring non-breeding contracts, we keep these varieties safe, healthy, and
away from money-hungry pet stores.
Here's a short list, followed soon by pictures:
Dwarf (genetic dwarfs, not just small rats)
Harley coats (long-haired, interestingly, discovered at a pet store in Washington years ago, but aren't here yet)
Down-Under (also in petstores in CA and WA, but not here)
Roans (start out with color, fade out to white as they age)