If you’re using BibTeX and LaTeX and are doing any kind of scholarly/humanistic work, I’m sure you’ve run into this annoying problem: BibTeX always complains when a book has both an author and an editor. That’s a problem when, say, you want to include

Gödel, K., 1986. Collected Works, vol. I. S. Feferman et al., eds. Oxford: Oxford University Press.

There is a wonderful package that allows you to generate new BibTeX bibliography styles based on a large number of customization options: custom-bib.  It comes with one big master bibliography style merlin.mbs from which your custom style is generated. I’ve produced a modified file which will also print both author and editor for a book that has both. 

Merry Christmas.