Niven is a frequent collaborator; see his other contributions under Niven w/J. Pournelle, Niven w/EM Lerner, Niven w/S. Barnes, Niven w/Pournell, Flynn and Niven w/GC Johnson.

Tannin-Secretion Pills
Artificially darkens skin, for skin protection.

Crashlander (1994)

Tasp - right where you live
A device that induces a current in the pleasure center of the brain, at a distance.

Ringworld (1970)

Teaching Chair
No-frills teaching machine.

Rammer (1991)

Tractor-Mounted Robot
A repair robot on tractor treads.

One Face (1965)

Translator Discs
Wearable devices that wirelessly connected to a speech translation computer.

Ringworld (1970)

Twing - twine by NASA
Used in the hold of spaceships to keep articles all together, and to prevent them from floating around in free fall, or falling during periods of acceleration.

Protector (1973)

Variable Sword - better than Ginsu
A sword that could vary in length, and cut through anything.

Ringworld (1970)

Webeye - Logitech endpoint
Communications device with a camera, microphone, zoom lens, projector, etc.; can be sprayed on.

The Ringworld Throne (1996)

Womb Room - return to the control room
The ultimate ship's bridge.

A World Out of Time (1976)

Wunderland Treatymaker - peace through power mining
A weapon based on a power mining technique - a bit more advanced than a shovel.

Ringworld Engineers (1980)

Young-Forever
A very particular formula for human immortality, which solves the most serious attendant problem (population explosion).

A World Out of Time (1976)

Zero-Time Jail - no time off for good behavior
A building in which an energy field prevents time from passing.

A World Out of Time (1976)