Ask HN Developers: Portfolios for Job Interview

I have a job interview with a consulting firm on Wednesday, and they have implied very loosely that I should have some work samples to show them. I've never had an interview in-person before that has asked me for these things; they have all pretty much gone along with my resume and any references I may have provided. How should I prepare for this type of interview, what should I bring, etc.? I'm thinking of going to Fedex Office tomorrow and getting some screenshots of applications and sites I've done printed up on 8.5x11" paper in full color, but will this be enough?