Actually, unless they ask for your portfolio with your application, I woudn't even worry about it, because people don't use portfolios in the business world. Your resume and cover letter should do all the talking for you ... then if they like what that says, they will call you in for an interview. At that time, you could bring some of it with you, just in case they have an interest in seeing it (or you can ask, when you book the interview).
If you are hiring on for a business job, I'd place the appropriate items in a briefcase, not a portfolio. A portfolio is for artists ... not business people.
Maybe have folders for each type of item in your briefcase: one for letters of reccomendation and referrals, one for spec sheets, trend reports, marketing plans (only a small sampling of your best), but probably not one for art work and photos ( they might not fit, anyway ... and they probably won't want to see them anyway, unless you are interviewing for a job in an art/grpahics dept.) That way, during the interview, if it seems appropriate, you can state that you have those items with you and offer to show them, if they are interested. It won't hurt to have them with you, just in case. However, most likely, they won't be interested. Don't push it ... you want to look like you are already in the business world ... not applying for school.
Make sure that any letters and work are copies .... just in case they want to keep them with your application.
