The Offworld Designs web site lists two new shirts.  The first is a Serenity Valley shirt in brown, depicting the Serenity Valley logo and the slogan “All gave some, some gave all”.  Unless I miss my guess, this is a reference to the battle discussed in the Firefly TV series and Serenity movie.  The second is a black shirt  depicting a hex-based logo and the words “Cardiff Weevil Retrieval Unit“.  This refers to the BBC series Torchwood.