DE-crypting (trivial case)

Fellow C'punks: I was wondering if anyone knew of software that does decryption of weakly encrypted messages, i.e., similar to ROT13, but perhaps ROT(x) where 0<x<26? Or maybe a bit more sophisticated, but not even at the single DES level? Also...anyone know of any histogram software? i.e., I input a file, it counts how many letters of each type, and outputs it in a table and/or a graph? If not, I'll have to (horrors!) write code! Kindest regards, Dave