In NCAA football, can a receiver tap the ball to another receiver, similar to a volleyball pass. I thought once an offensive receiver touched the ball it was an incomplete pass if a defensive player didn't touch the ball in between.
Yes, an eligible receiver may tap or bat the ball. Here is a relevant interpretation from the NCAA Rulebook.
Approved ruling 7-3-6 VIII (Page FI-41)
While airborne and in bounds, eligible receiver A89 touches a forward pass when he propels it toward: (a) eligible receiver A80, who catches the pass; or (b) B27, who intercepts the pass. RULING: Legal play, and the ball remains live in both (a) and (b). A89 has batted a forward pass (Rules 2-4-3, 2-11-3 and 9-4-1-a).
The mentioned 9-4-1-a rule seems especially relevant:
While a pass is in flight, only a player who is eligible to touch the ball may bat it in any direction (Exception: Rule 9-4-2).