Have: Duplicates. I will definitely trade these for any cards that I don't have from the same set, and could possibly be persuaded to trade them for cards from other sets, or even for cards I already have.

Want: Any cards I don't have to help complete my sets.

For an up to date list, you can always go here: http://www.steamtradematcher.com/quickmatch/76561197960275943
I'm also willing to trade if you need one of my dupes but don't have anything I'm missing - as long as it's not a net loss for me, I'm up for it!