Freq.

From Positron Software:

This program counts the number of each letter in a given block of text. It allows you to import text or type directely into the program. It gives the results in a table that can be saved for future reference. It is a great utility for doing things such as frequency analysis for decrypting direct substitution cyphers such as a=e, c=f, d=g. This utility will help you solve those types of codes. It is nothing fancy, but I wanted a utility that does this but there were none available on Version Tracker so I offer this to you. Realbasic source code available upon request.