Reference

Frequency Analysis

Articles

Password Entropy and Length Correlations
A Little Rant About Passwords
Beware of Bad Crypto!

Simple Ciphers

Archon's Online Encoder

Downloadable Ciphers

Binary Encryptor/Decryptor
1337 (leet) Encryptor/Decryptor
Hex Encryptor/Decryptor
Rot-13 Encoder/Decoder
Pair Switch Encoder/Decoder
Discrete Cosine Transformation Encoder/Decoder
HTML Character Code Encryption