I thought about creating one for my mother before her school system got a integrated system that makes this (in)convenient. After looking at the problem some I came to the conclusion that a PDF form would be the best solution because:
Everyone seems to use an IEP slightly differently... and everyone thinks that their way is the right one.
It seems that there are real differences in IEPs between districts. So I don't think that there is going to be any generic software out there.