Essential Accessories - Official TF2 Wiki
Unusual Cap - Official TF2 Wiki
PASS Time Early Participation Pin - Official TF2 Wiki
Plug-In Prospector - Official TF2 Wiki
Bonk Boy - Official TF2 Wiki
Top Notch - Official TF2 Wiki
A Well Wrapped Hat - Official TF2 Wiki
Ludicrously Lunatic Lunon Fedora - Official TF2 Wiki
Under Cover - Official TF2 Wiki
NY Times reports on Team Fortress 2's hat obsession : r/tf2