I've actually been thinking about this for a few weeks as I have a programming background and this could be done with exceptions.
The only problems I see monetizing this type of program are: Trust. You would have to be able to trust the software. I would be a little weary of having to add usernames and passwords to a software program for my affiliate accounts. This would need to be done some how.
Also, the different way poker sites offer the statistics makes this very difficult for someone to do for free. In other words it may be one thing to grab information from Absolute and Paradise, but then Full Tilt uses Excel and CSV formats. Having a prgram match these formats would be very time consuming and may not allow users to add new affiliates that were not included in the software release requiring the author to update the software on a regular basis.
I have played around with doing this for myself and it can be done for a few sites. Other sites however are a little tricky.
But like I was saying I find it hard to believe that affiliates will put information like usernames and passwords into a software program. You would need extensive testing and 3rd party auditing to insure the integrity.
Just a few thoughts on this...
I'm welcome to ideas as this has been floating around my brain for a few weeks now.