The String class in Actionscript 3 has twenty methods for manipulating string data. I have found a free String class here that has an additional thirty one methods for manipulating strings. Some of the features include adding quotes, capitalizing and reversing strings. This class is straightforward to use, you need to firstly download the file and extract it. Then place the class file in the same directory as your FLA file or setup a source path to your file. You then can start coding with this class. The documentation for this class can be found inside the AS3 class file.
Below is an example of the String util where I have used the captialize method to capitaize the characters in the string.
var myString:String = "This is some text by ilike2flash.";
var newString:String = StringUtils.capitalize(myString);