The quick set tenon jig is designed to quickly move between cut positions using a lever so that both sides of a tenon can be cut without having the flip the workpiece. This makes for more precise joints and faster operation. The jig can also take templates so that double or triple tenons can be cut with it without re-mounting the workpiece.
An older, 2008 article
Harlan Opie's quick-set tenon jig
Dan Chernoff's quick-set tenon jig
Elyasaf's tenon jig
Dave Tenney's tenon jigs
Carsten Avenhaus's tenon jig
Yiyong Leng's tenon jig