fSekrit provides you with an encryptable notepad that will allow you to save information within an .EXE file.

This a bit of an old app but it still works quite well for storing your non-State secrets. ;) And best of all if you share an encrypted piece of info, the recipient need not have fskerit all they need is the correct passphrase. Any file created with fskerit uses AES/Rijndael in CBC mode, with 256-bit key size and the unencrypted data is never saved to your disk providing an added bit of security.

There is no UI to speak of, you write your note, set your password, name the file and save. Encryption doesn't get much more straightforward than that. Make sure you keep track of password, or you'll be out of luck!