There is alot of ways to encrypt the data your sending, you can use a secure IM to send secure messages (check the Chat links, pinned topic), or if you must use AOL, then you might want to get PGP and use a textpad, encrypt the message, then paste it into AOL and send it, the recipient MUST also be able to decrypt the message, so you will have to set them up to receive.
PGP Desktop
http://www.pgp.com/products/personal.html