I have been working on an achivement and point system for quite some time now, unable to get a direct connection to work I resorted to a password system, but then I thought why not URL's, I can create pages to gather codes from URL's and put them on the players account on my site.
The only question is, can the game launch URL's? And if so, how?
http://www.rmxp.org/forums/index.php?topic=24130
I remember finding a script on RMXP.org that did an HTML Links sort of thing, and I managed to find this. Simply follow the instructions there and you're all set. :)
It should work at least, it's not something advanced or intricate like a battle system or something.