Triangle Concept - This concept is all about making a triangle with the routes that are being ran. By doing this, you've confused the defense to a point where someone will be open. My favorite way of doing this is by using a formation where there are 3 receivers on one side(TE's and HB's count).
I put the slot WR on a streak, the outside WR on an inside slant, and the TE on an outside slant out of the Shotgun Y-trips HB wk formation. It makes a small triangle where they all intersect each other. It sets up another defensive confusion, leading to a mismatch, which leads to completions.
This is one of those things that works in zone very well, and works in man even better.