A dirty hack to combine multiple BibTeX files into one, with a few formatting and tidying conventions added in.
This small python program was born when I began to write my doctoral dissertation at the University of Nebraska. Because I wished (for some sick reason) to write my dissertation in LaTeX, I needed to convert my EndNote (gag!) reference libraries into BibTeX, which was easily done. I then had to combine them into a single BibTeX file, organize them by journal name, sort them by publication date within each journal, and strip out all the crap that EndNote drops into its BibTeX files.
So, tidybib fills that need. Long story short, I'm anal about BibTeX and LaTeX source file formatting and I wrote a quick hack to satisfy my need for consistency and structure. It's sad, really.
No guarantees that this will work for you, but it should barf pretty hard if you try and feed it files that aren't formatted as it expects. One thing to make sure of is that no email addresses (i.e. no ampersands) are present in the BibTeX fields, and that each field only occupies a single line of text in the input files.