I wasn't happy with the available libraries used to scroll text across LCDs, so I created GKScroll.
Some of the limitations of the existing libraries included:
Limited text length (how long the string could be)
Short strings resulted in large gaps between the end of the string and the beginning as it scrolled
My library solves these issues. You can have a very long string and it will scroll all of it and repeat over and over.You also get to choose the buffer (how many spaces to leave after the string before it repeats).
I have posted it for Download Here: http://garrettkendrick.com/2014/01/gkscroll-library-for-arduino/
Please let me know if you have any suggestions or concerns.