Well, part of trading is knowing what the person you're trading with is seeking, right? For me, I collect the following (in order of importance):

Rachael Yamagata (ANYTHING)

Fiona Apple (clippings and magazines with her on the cover)

Christina Aguilera (clippings & magazines with her on the cover)

Evanescence (clippings & magazines with her on the cover)

Elisha Cuthbert (clippings & magazines with her on the cover)

SpongeBob SquarePants (various toys and things)

Clippings of the following: Nikka Costa, Wicked the Musical/Idina Menzel, Imogen Heap, Zooey Deschanel, David Duchovny

Things I collect for others:

Clippings of: Britney Spears, Rihanna, Alicia Keys

* Remember that just because you have things that I like, doesn't mean I want them. I may already have them. Also, please try to be fair when offering trades :) *