Hi Jon,
Jonathan means 'God's Gift' and its origin is Hebrew.
Joanna means 'God is Gracious' origin is English, Polish
Alternatives: Evena (Eastern European), Gianina (Italian), Gianna (Italian), Giovanna (Italian), Ivana (Czech), Ivanna (Russian), Jaine, Jana (Czech, Polish), Janna, Jannike (Scadinavian), Jayne, Jeanne (French), Jehanne (French), Juana (Spanish).
Nicknames: Ivanka (Czech), Jan, Janey, Janie, Jaynie.
http://www.cool-baby-names.com