Tons, it just depends on how you are breaking them up, the structure of your data, and the size of the files.
If it is a direct split, eg splitting an xml table of 1000 rows into 2 files of 500 and 500, I suggest using a scripting language such as perl.
If it is splitting it out into different splits of data, eg like a database, I would probably recommend XSLT 2.0