(Please click through to Think Geek. They might be having a sale!)
Look, we know Hydra is supposed to be a largely clandestine organization. In public all they can do is give a tight hug and a whispered "Hail" in passing - visible Hydra logos aren't usually done. Which is kinda sad, since they have the coolest logo in all of the Marvel Universe. For our money a skull with tentacles will beat an eagle giving the side-eye any day, design-wise...