Positive time!
I think the last iteration swag doesn't appeal to the types of people you would find at bitcoin conferences. In a recent conversation, another forumite gave these characteristics:
-95%+ predominantly male
-higher education than average
-at the very least they already know about bitcoin and probably have general idea of the implications of blockchain technologies and decentralized systems
-have philosophical and political views that align more with libertarian and anarchist perspectives
-more than likely have a monetary incentive; or some variation of self-interest
My opinion is that you need a clean, simple t-shirt design with a company or product logo and your favorite from among these:
* Decentralize Everything
* Decentralized Solutions to Centralized Problems
* BitShares X: Decentralized Bank and Exchange
* BitShares ___: _______
* Life, Liberty, Property
* Reimagine Everything, with some visual aid to tell you what kind of things to reimagine