Bah! No one seems interested in my online highscore tutorial so I won't be doing the second part. Maybe its best I don;t reveal the encryption/security methods I use anyway.
If you haven't played Doukutsu Monogatari (cave story) yet I highly recommend it. Its a japanese sidescrolling platformer that has a great retro nintendoish feel to it. The bosses, dialogue and level design are excellent.