dist manipulation software?

Folks; Does anyone know of any pre-existing software for manipulating dist files (i.e. generating per-domain percentages from a dist file, merging two dist files, comparing two dist files, etc., etc)? I suppose anything that dealt specifically with lists of email addresses would work (that is, it doesn't necessarily have to handle the "Only addresses below this line" itself)...anyone have a pointer to such a thing? Charlie (who hopes he doesn't have to reinvent the wheel...)