What's a good resource to research archived ad campaigns in television and in print?

I'm working on a fictional period piece about the early 2000s, (2000-2003) trying to write several scenes about the threads and messaging of certain products:

Internet start-ups, automobiles, insurance, fast food and soft drinks, all the main staples of prime time advertising.

Not precisely sure what I'm looking for yet, just waiting for something to pop out at me.

What do you guys use for research like this?