My interest in public key encryption continues. I wanted to be able to actually use a tool to play so I wrote one.
It does these things:
1) Generate a key pair.
2) Extract a public key from a private key.
3) Manually enter public or private key.
4) Create a crypto text string from plain text input.
5) Extract plain text from a crypto string.
You can play with this at: http://genericwhite.com/rsaEncryptionDemo/
Code is available on github.