Hmm... if you want something to really surprise people and make them go "what was that" as you said.... perhaps some modulation of some kind. I noticed you dont really have anything in this category.
You could do with some flange, phase, tremolo, etc. perhaps. I don't know how strange you want things to sound for people to go "what was that?" but you could coax some crazy enough sounds out of these basic modulations. Depends upon your style of music.
EDIT: Cripes, i see you're selling a flanger, but consider some other modulation.
EDIT 2: A whammy?
MIJ Lefty Jazzmaster w/ Ducan Antiquity II's--->Fuzz Factory--->Fulltone OCD V2--->BYOC triangle muff clone--->Rat II--->EHX US Small Stone--->Ernie Ball VP Jr.--->Dano Tuna Melt--->Boss DD-20--->Magicstomp I
into a Peavey Classic 50 212