His contribution to Trek is significant: he wrote the Trouble With Tribbles episode that has achieved cult status with fans of the franchise and even spawned a return on the Deep Space Nine series out many years later.
Several years ago he wrote a book about writing science fiction. I read Worlds of Wonder several times since then. I hoped to have him sign it at one of the Worldcons that I’ve attended, but he hasn’t been to them.
The information in the book isn’t all earth-shaking, but what parts are definitely do. The chapters on tension and on sex (granted, that part is not for everyone) alone are very useful – and the entire book makes for entertaining reading.
It actually isn’t only of use in writing SF but in other genres too. Just the chapter on a newer writing verb tense was interesting!