A DVD with all the most popular YouTube videos burned onto it. May be a bit more embarrassing than anything else, but hey, it's definitely a sign of the times. :-)

What about a fashion, music, or entertainment magazine? Something that shows more than just the news - maybe a copy of People? Maybe a listing of top music charts - like adult contemporary, hip hop, country, etc. to show what music was listened to. A medical journal of some sort might be interesting - somthing that shows what medical concerns and treatments are common today.

How about an iPod - maybe you could find one that doesn't work - same with a cell phone. Those would be two ways of showing some of our technology without taking up too much space. If I remember geometry correctly, 8 cubic feet would be 2' x 2' x 2', right?

This is what I could think of for now. I'm not sure if this is what you are looking for or not.

TV Guide
some catalog - something to show the current prices of *stuff* - ie Sears or JC Penney etc
Real estate ads

(cool idea Tom!)

love your idea! good luck with your project
not sure how much $$ you have to work with
here are some ideas:

photos of current fashion - kids, adults, sports, professional, fancy, couture
photos, menus of popular foods, restaurants - can you get plastic food samples like they have restaurants?
listing, images, DVD of popular movies and TV
Michael Jackson - hee hee
show current "Green" initiatives
some kinda current political agendas
list and images of current endangered species
list of current jargon, slang terms
current do's and don'ts
modern day appliances - the single serve coffee device, iphone, air cleaners
candy
shoes
art exhibit literature, photos
some kinda representation of the web world - blogs, twitter, social network

Beautiful!!

great ideas all...