You can pay real money for extra character slots, as well as boosters to enhance your experience and resource gains. (gap4.com)
This brings up a very nice keyboard which is spaced out really well with a dedicated row up top for numbers, accents and all those kind of extra characters at the bottom. (ereaderspotlight.com)
These are fairly minor features in terms of your time with the game, but add extra character of their own. (nintendolife.com)