Another cheap but precious smartphone gadget slimming down my EDC kit:
http://www.ebay.com/itm/391333526724 It makes possible to connect any regular USB memory stick or some USB devices (like mouse or keyboard) to your Android Smartphone and has a minimal physically possible size. It's so thin, that I'm carrying it in the camera lens' hole of my phone belt clip between two pieces of tape. The regularly sized OTG piece is going off my keychain forever!