Two things that I would love to have in every portfolio and for some reason tend not to see very much:
1) Citing your partner(s) name. It gives me an insight into their work as well as yours. And is just the right thing to do. Wouldn't you want to be called out in someone else's book?
2) Citing every contribution you personally made to the piece. If you took the photography, say so. If you are an art director and wrote the headline yourself, say so. Knowing the extent of your skills is so helpful, it gives me a deeper perspective on what you bring to the table.