webcrypt is a Java web browser with built in modules for encrypting and cryptanalyzing some classical ciphers. It has a modular design which easily allows introducing any desired cipher method and new cryptanalysis tools.
I utilize webcrypt in my cryptography courses to teach students cryptographic algoritms and cryptanalytic techniques. An available administrator's version lets me auto-generate plaintexts for students to encrypt during algorithm implementation assignments, and ciphertexts for cryptanalyzing during cryptanalylsis assignments.
Here's a lecture (PDF slides) which explains how webcrypt is used to cryptanalyze the following encryption schemes:
If you would like to try to cryptanalyze the described examples you will need to have Java 1.4 or higher on your system. Then: