Source code or components for specific algorithms.
[>] Rijndael
The Rijndael algorithm was chosen for the new official U.S. cryptographic standard AES. It's a variable length block cipher, and supports a variety of key lengths.
[>] TwoFish
TwoFish is another variable length algorithm, capable of using key lengths of up to 256 bits. It was a finalist for the AES, beaten only by Rijndael, and is based on the Blowfish algorithm.

A Visual Basic implementation of TwoFish is available if you visit their homepage.